1. Practical Challenges

#	Challenge	Difficulty	Status	Implementation Notes
1	Personal Time Tracker	(E)		Store data in SQLite or JSON. Use datetime module for tracking.
2	Terminal Habit Coach	(E)		Use SQLite for persistence. A simple argparse or click CLI.
3	Smart Expense Splitter	(E)		Model as a graph problem to simplify debts (e.g., Min-Cost Max-Flow or simpler heuristics).
4	Self-Hosted Link Shortener	(E)		Use a simple web framework (Flask/FastAPI) and a database for mapping. Hash the original URL for a basic slug.
5	Universal Unit Converter API	(E)		Store conversion factors in a JSON or config file. Expose via a simple HTTP API.
6	System Health Dashboard	(E)		Use psutil library to get CPU/RAM/Disk stats. A simple web dashboard or CLI.
7	Interview Prep CLI	(E)		Store Q&A in JSON/YAML. Implement spaced repetition using a simple date-based algorithm.
8	Smart Download Manager	(M)		Use threading for concurrent chunks. requests for HTTP Range headers (pausing). hashlib for checksums.
9	Encrypted Notes Vault	(M)		Use cryptography library (Fernet) for symmetric encryption. tkinter or PyQt for minimal GUI.
10	Git Commit Quality Bot	(M)		Implement as a pre-commit hook. Use regex to check message format (e.g., 50-char limit for subject).
11	Universal Log Analyzer	(M)		Use regex for parsing common formats (Apache, nginx). pandas for aggregation. Plotly or matplotlib for dashboards.
12	Static Site Generator	(M)		Use markdown library to convert. Jinja2 for templating. Manage posts, tags, and drafts.
13	Media Library Organizer	(M)		Use APIs like TMDB (movies) or MusicBrainz (music). os and shutil for file operations.
14	Password Data Breach Checker	(M)		Use hashlib (SHA-1). Implement k-Anonymity by sending only the first 5 hash chars to HIBP API.
15	Dotfiles Manager	(M)		Core logic involves creating/managing symlinks from a central repo to home directory locations.
16	Markdown Knowledge Base	(M)		Use Whoosh or Elasticsearch for full-text search. Parse links (regex or AST) to build the graph.
17	Personal Finance Dashboard	(M)		Use pandas to read and analyze CSVs. matplotlib or Plotly for visualization.
18	Image Compression Tool	(M)		Use Pillow (PIL) for image operations. Expose quality (lossy) and optimize (lossless) parameters.
19	Resume/Portfolio Generator	(M)		Use Jinja2 to render JSON data into HTML/Markdown templates. WeasyPrint or pandoc for PDF.
20	Pluggable Notification Hub	(M)		Design a core Notification class and provider-specific subclasses (EmailProvider, SlackProvider).
21	Data Import Wizard	(M)		Use pandas to infer dtypes. SQLAlchemy to generate tables and insert data into SQLite.
22	Screen Time Tracker	(M)		OS-specific APIs needed (e.g., pywin32 on Windows, AppleScript on macOS) to get active window title.
23	Smart Screenshot Tool	(M)		Use mss for screen capture. PyQt or tkinter for drawing annotations. Tesseract (OCR) for search.
24	Email Newsletter Engine	(M)		Use smtplib for sending. Jinja2 for templates. Manage subscribers in a simple DB (SQLite).
25	Document Template Filler	(M)		For DOCX, use python-docx. For PDF, PyPDF2 or reportlab (harder) or find a template library.
26	Smart Calendar Merger	(M)		Use icalendar library to parse .ics files. Implement logic to merge event lists and find overlaps.
27	Photo De-Duplicator	(M)		Use Pillow and an image hashing library (imagehash) for perceptual hashing (aHash, pHash).
28	Code Snippet Manager	(M)		Use Pygments for syntax highlighting. Store snippets in SQLite with tags.
29	Dataset Explorer UI	(M)		Use pandas-profiling or sweetviz for reports. Build a simple Streamlit or Dash UI.
30	Offline-first PWA To-Do App	(M)		Requires Service Workers for caching. Use IndexedDB or localStorage for client-side storage.
31	Personal API Key Vault	(M)		Use a master password to derive an encryption key (e.g., PBKDF2). Store encrypted keys in a local file/DB.
32	Privacy-Friendly Analytics for Static Sites	(M)		A simple backend (FastAPI) to log pageviews (URL, referrer). No cookies. Store in SQLite.
33	Cross-Platform Clipboard Sync	(H)		Requires a server (e.g., Flask) and clients. Use UDP broadcast for LAN discovery. cryptography for E2E.
34	Command Palette for Your OS	(H)		Needs a global hotkey listener. PyQt for the UI. Plugin system can use simple Python modules in a folder.
35	Local Search Engine	(H)		Use Whoosh (pure Python) or Solr/Elasticsearch for indexing. Tika for parsing docs (PDF, DOCX).
36	Backup Orchestrator	(H)		Implement rsync-like logic (check file mtime/hash). Use zlib or lzma for compression. Manage snapshots.
37	Task Queue + Worker System	(H)		Use Redis LISTs (LPUSH/BRPOP) for a simple queue. Celery is the full-featured version.
38	CLI Email Client with Rules	(H)		Use imaplib and smtplib. sqlite for offline caching. Rule engine can be simple JSON/YAML.
39	Local File Sync (rsync-lite)	(H)		Implement the rsync algorithm (rolling checksums) or a simpler mtime/size check. socket for transfer.
40	Custom Shell	(H)		Parse input, fork and exec commands. Implement pipes (pipe()) and redirection (dup2()).
41	Config-as-Code Manager	(H)		Use jsonschema for validation. Logic to diff current state vs. desired state and apply changes.
42	Encrypted File Sharing over WebRTC	(H)		Requires a signaling server (e.g., WebSocket) for handshake. pywebrtc for data channels.
43	Data Pipeline Runner	(H)		Represent DAG as a graph (e.g., networkx). Use topological sort to find execution order.
44	IoT Home Metrics Collector	(H)		Use MQTT (e.g., paho-mqtt) for data ingest. InfluxDB (time-series) and Grafana (dashboard).
45	Local AI Note Summarizer	(H)		Integrate a small model like distilbart-cnn via transformers. PyMuPDF for PDF extraction.
46	API Gateway Proxy	(H)		Use a web framework (FastAPI) to proxy requests. Implement rate limiting (e.g., token bucket algorithm).
47	Containerized Dev Environment Creator	(H)		Analyze repo (e.g., requirements.txt, package.json) to guess base image. Generate Dockerfile text.
48	Knowledge Quiz Generator from Text	(H)		Use an LLM API (e.g., Gemini) or a local model. spaCy for entity/noun chunk extraction helps.
49	Screen Recording + Annotation Tool	(H)		Use mss + cv2 to capture and write frames to video. PyQt for overlay/controls.
50	“Life Dashboard” Aggregator	(H)		Requires writing multiple API clients (Google Calendar, Todoist, bank). A central Streamlit or Dash UI.

2. Algorithmic Challenges

#	Challenge	Difficulty	Status	Implementation Notes
1	Approximate Set Membership (Bloom Filter)	(E)		Implement a bit array and multiple hash functions (e.g., variations of mmh3). Test false positive rate.
2	Advanced Interval Scheduler	(M)		Classic DP problem. Sort by end times. dp[i] = max weight using intervals up to i.
3	Autocomplete Engine	(M)		Use a Trie (Prefix Tree). Store frequency in nodes for ranking.
4	Approximate String Matching	(M)		Implement Levenshtein distance (DP). For speed, explore BK-trees or n-gram indexing.
5	K-d Tree & Nearest Neighbors	(M)		Build tree by recursively splitting on median. k-NN search requires backtracking (priority queue).
6	Consistent Hashing Library	(M)		Map nodes/keys to a circle (e.g., hash(key) % 360). Virtual nodes improve distribution.
7	Generic DP Visualizer	(M)		Needs a UI (tkinter, PyQt, web). Pass the DP table and recurrence; step through filling it.
8	Top-K Frequent Items in Stream	(M)		Implement Misra-Gries or Space-Saving algorithm. A hash map is the core data structure.
9	Randomized Algorithms Suite	(M)		Quickselect (partitioning), Skip Lists (probabilistic linked lists), Treaps (BST + heap).
10	Matrix Algorithm Lab	(M)		Implement matrix as list-of-lists or numpy. Strassen is a recursive, divide-and-conquer algorithm.
11	HyperLogLog Implementation	(M)		Core is hashing items and storing the max number of leading zeros in the hash.
12	Game Tree Search Framework	(M)		Implement Minimax. Alpha-beta pruning is an optimization that prunes unpromising branches.
13	Clustering Algorithms Suite	(M)		k-means (centroids), k-medoids (data points), DBSCAN (density-based). matplotlib for visualization.
14	Edit Distance with Custom Costs	(M)		Standard Levenshtein DP, but use the custom costs in the recurrence relation.
15	Online Caching Simulator	(M)		Implement cache as a dict/hash map. LRU needs a doubly-linked list or OrderedDict.
16	Text Justification Engine	(M)		DP approach: dp[i] = min badness for justifying words i to n.
17	Large Integer Arithmetic Library	(M)		Store numbers as arrays of digits. Implement schoolbook add/subtract. Karatsuba or FFT for fast multiply.
18	Dynamic Shortest Paths Service	(H)		For edge weight changes, Dijkstra is too slow. Research D* Lite or algorithms for dynamic graphs.
19	Constraint Solver (Mini-SAT)	(H)		Implement DPLL: unit propagation, pure literal elimination, and branching. Clause representation is key.
20	Generic Flow Library	(H)		Start with Edmonds-Karp (BFS for augmenting paths). Min-cut from residual graph.
21	Persistent Data Structures Kit	(H)		Key is "path copying." When modifying a node, copy it and its ancestors.
22	Rope-based Text Editor Core	(H)		Implement a binary tree where leaves are strings. Insert/delete involves splitting/merging nodes.
23	2D Range Query Library	(H)		A 2D Fenwick tree (BIT) or segment tree. Can be a 1D tree where each node is another 1D tree.
24	Suffix Automaton Toolkit	(H)		Complex state machine. Each path from root = a suffix. Online O(n) construction is possible.
25	Streaming Quantiles	(H)		CKMS or KLL algorithms. Maintain a compact summary of the stream, not all data.
26	Suffix Array + LCP	(H)		Build suffix array (e.g., O(n log n) or O(n)). Kasai's algorithm for O(n) LCP array.
27	Graph Isomorphism Checker (Heuristic)	(H)		No known poly-time algorithm. Use heuristics like Weisfeiler-Lehman (color refinement).
28	Geometry Engine 2D	(H)		Use atan2 for angles. Convex hull (e.g., Graham scan). Point-in-polygon (ray casting).
29	On-Disk B-Tree Index	(H)		Focus on serializing/deserializing nodes (pages) to disk. Each node is a fixed-size block.
30	Matching Engine (Order Book)	(H)		Use two priority heaps (min-heap for asks, max-heap for bids) or sorted data structures.
31	Multi-dimensional Knapsack Solver	(H)		DP state becomes dp[i][w1][w2].... For large W, use branch-and-bound.
32	Lossless Compression (LZ77/78)	(H)		LZ77 (sliding window, (offset, length) pairs). LZ78 (dictionary of seen strings).
33	Scheduler with Deadlines & Penalties	(H)		Sort by deadlines. DP or greedy approach with a disjoint set (for finding available slots).
34	Parallel Sort Library	(H)		Parallel merge sort is a good start. Use threading or multiprocessing to sort subarrays.
35	Disjoint Set with Rollback	(H)		DSU (Union-Find). To rollback, don't use path compression. Store a stack of changes.
36	Temporal Event Store	(H)		Use an interval tree to index events by their time ranges for efficient queries.
37	Routing with Turn Penalties	(H)		Model graph with edges as (u, v) pairs. Or, model graph with nodes as (u, v) edges to store turn costs.
38	Pattern Mining in Sequences	(H)		Apriori-based (GSP) or PrefixSpan. Involves building and mining prefix trees.
39	Automatic Timetabler	(H)		Model as a graph coloring problem (courses=nodes, conflicts=edges). Use heuristics (e.g., backtracking).
40	Bin Packing Variants	(H)		NP-hard. Implement heuristics: First Fit, Best Fit, First Fit Decreasing.
41	Image Seam Carving	(H)		DP. Find lowest-energy seam (path) from top to bottom. Energy = pixel gradient.
42	Auto-Completion with Language Model Prior	(H)		Combine Trie search (for prefix) with n-gram probabilities (for ranking).
43	Route Planning with Constraints	(H)		Modify Dijkstra/A*. For "must-visit," find path segments (A->B, B->C). For "forbidden," remove nodes.
44	Polygon Triangulation	(H)		Ear clipping algorithm (O(n^2)) is feasible. Find a convex vertex ("ear") and clip it.
45	Subsequence Automaton	(H)		Build an automaton in O(n*k) (k=alphabet size) where next[i][c] = first occurrence of c after pos i.
46	Dynamic Connectivity Structure	(I)		Requires complex data structures like a link-cut tree or a fully dynamic graph algorithm.
47	Regex Engine	(I)		Convert regex to NFA (Thompson's construction), then NFA to DFA (subset construction).
48	Versioned Key–Value Store (LSM-tree)	(I)		Implement an in-memory memtable (e.g., skiplist) and on-disk SSTables. Compaction merges SSTables.
49	Map Label Placement	(I)		NP-hard. Heuristics like simulated annealing or greedy placement (e.g., place most constrained labels first).
50	Multidimensional Index (R-Tree)	(I)		Tree of Minimum Bounding Rectangles (MBRs). Splitting nodes (e.g., quadratic or linear split) is the hard part.

3. Emulation / Modeling Challenges

#	Challenge	Difficulty	Status	Implementation Notes
1	Cellular Automata Lab	(E)		Use a 2D array for the grid. The core logic is a function that computes the next state from neighbors.
2	Chip-8 Emulator	(M)		Implement 35 opcodes, 4K RAM, 16 registers. pygame or tkinter for 64x32 display.
3	Virtual File System	(M)		Use a tree-like class structure (Node, File, Directory). Serialize the root to a single file (e.g., pickle or JSON).
4	Traffic Intersection Simulator	(M)		Discrete event simulation. Events: car_arrives, light_changes. Use a queue for cars.
5	Boids Flocking Simulation	(M)		Each 'boid' agent follows 3 rules: separation, alignment, cohesion. Update all positions each tick.
6	Elevator System Model	(M)		Model elevators and floors as objects. Use a discrete event queue. Test different scheduling algos (e.g., SCAN).
7	Operating System Process Scheduler	(M)		Simulate a process queue and a clock. Implement algorithms (RR, SJF) by deciding which process runs next.
8	Cache Simulator	(M)		Simulate memory addresses. Map address to cache set/line. Implement LRU/FIFO replacement.
9	Epidemic Spread Model	(M)		SIR model: agents are (S)usceptible, (I)nfected, or (R)ecovered. p_infection and recovery_time are key params.
10	Neural Network From Scratch + Visualizer	(M)		Implement numpy-based layers (Linear, ReLU). Backpropagation is manual chain rule. matplotlib to show loss.
11	Pedestrian Crowd Simulation	(M)		Social forces model: agents have a goal and are "repelled" by obstacles and other agents.
12	DNS Resolver Simulation	(M)		Simulate root, TLD, and authoritative servers (e.g., as dicts). Implement recursive queries and a cache (dict with TTL).
13	Music Synthesizer	(M)		Use numpy to generate wave arrays (sine, square, saw). pyaudio to play. ADSR envelope shapes the volume.
14	Blockchain Simulator	(M)		Block class (hash, prev_hash, data, nonce). Blockchain class (list of blocks). PoW = find nonce.
15	Virtual Machine for a Toy Bytecode	(M)		Define opcodes (PUSH, POP, ADD). Implement a stack, instruction pointer, and a loop that fetches/decodes/executes.
16	Weather Pattern Cellular Model	(M)		2D grid. Rules for how pressure/wind/moisture cells interact and move.
17	Scheduling Visual Playground	(M)		Visualize Gantt charts for different job sets and algorithms (e.g., FCFS, Shortest Job First).
18	Genetic Algorithm Playground	(M)		Implement: population, fitness function, selection (e.g., roulette), crossover, mutation.
19	Particle System Engine	(M)		Manage a list of Particle objects. Each has position, velocity, lifetime. Update all each frame.
20	Queueing System Simulator	(M)		M/M/1: Poisson arrival, exponential service time. Use a discrete event queue. Track wait times.
21	Multiplayer Network Lag Simulator	(M)		Intercept packets (or simulate) and use a queue with time.sleep to add latency/jitter. Randomly drop packets.
22	Game Boy Emulator Core	(H)		Sharp SM83 CPU (like Z80). Memory-mapped I/O. PPU (Pixel Processing Unit) is complex (sprites, tiles).
23	Simple RISC CPU Simulator	(H)		Simulate pipeline stages (Fetch, Decode, Execute, Memory, Writeback). Detect/handle data and control hazards.
24	Network Stack Simulator	(H)		Simulate packet loss/reordering. Implement TCP congestion control (slow start) and re-transmission.
25	Solar System N-Body Simulation	(H)		Calculate F_gravity = Gm1m2/r^2 between all pairs. Use an integrator (e.g., Euler, Verlet) to update pos/vel.
26	Warehouse Robotics Simulator	(H)		Use A* or Dijkstra for pathfinding. Collision avoidance (e.g., locking grid cells or paths).
27	Memory Allocator Simulator	(H)		Implement malloc (find free block) and free (coalesce blocks). Use free lists. Visualize fragmentation.
28	RL Environment Sandbox	(H)		Implement OpenAI Gym-style API: step(action), reset(). Gridworld needs a render() method.
29	Stock Market Order Book Simulator	(H)		Core is a matching engine (see Algos #20). Add agents that place market/limit orders.
30	Air Traffic Control Simulator	(H)		2D/3D space. Planes have flight plans. Detect conflicts (paths too close).
31	Voxel-based Terrain Engine	(H)		Render world in "chunks." Use Perlin noise for terrain generation. Greedy meshing for optimization.
32	Ray Tracer	(H)		For each pixel, cast a ray. Find closest intersection (sphere, plane). Recurse for reflection/shadows.
33	City Power Grid Simulator	(H)		Model as a graph. Nodes=stations/users, Edges=lines. Simulate power flow and cascading failures.
34	Planetary Climate Toy Model	(H)		Energy Balance Model: E_in (solar) vs E_out (black-body radiation). Add greenhouse effect, albedo.
35	Compiler IR Visualizer	(H)		Use a parser generator (e.g., ANTLR) to build AST. Convert AST to basic blocks (e.g., 3-address code).
36	Packet Sniffer + Playback Simulator	(H)		Use scapy or pcap to capture. Save to .pcap file. Replay by sending packets with original timings.
37	Database Transaction Simulator	(H)		Implement 2-Phase Locking (2PL). Build a "waits-for" graph to detect deadlocks.
38	Robot Arm Kinematics Simulator	(H)		Forward Kinematics (FK): matrix transforms for each joint. Inverse (IK): harder, (e.g., CCD algorithm).
39	Disaster Evacuation Simulator	(H)		Agent-based model. Use A* for pathfinding, but edge weights increase with "congestion" (other agents).
40	Logistics & Routing Simulator	(H)		Vehicle Routing Problem (VRP). Heuristics like Clarke-Wright savings or custom simulated annealing.
41	Economy Market Simulator	(H)		Agent-based. Firms produce, consumers buy. Simple supply/demand rules. Find equilibrium price.
42	Microservices System Emulator	(H)		Simulate services as threads/processes. Use RabbitMQ or ZeroMQ for messages. Inject chaos (kill service, drop msg).
43	Railway Network Signal Simulator	(H)		Model track as a graph of "blocks." Interlocks prevent trains from entering occupied blocks.
44	Virtual OS Boot Process Simulator	(H)		Simulate BIOS (find bootable device), bootloader (load kernel), and kernel init (init process, drivers).
45	Fluid in Pipes Simulation	(H)		Model as a graph. Use hydraulic principles (e.g., Hardy Cross method) to solve for flow/pressure.
46	Robot Swarm Simulator	(H)		Agents with simple local rules (like Boids) that lead to emergent global behavior (e.g., foraging).
47	Drones Delivery Simulator	(H)		Pathfinding (A*) + constraints (battery life, no-fly zones).
48	Fluid Simulation (2D Navier–Stokes-lite)	(I)		Grid-based. Requires solving for advection, diffusion, pressure. Use stable split (e.g., "Stable Fluids" by Stam).
49	3D Rigid Body Physics Engine	(I)		Detect collisions (GJK/SAT). Resolve collisions (impulse-based). Handle constraints (e.g., joints).
50	Neural Cellular Automata	(I)		"Grow" images. Each cell is a mini-NN that reads neighbor states and updates its own. Train (e.g.,
pytorch) to match a target.

4. Artificial Intelligence Challenges

#	Challenge	Difficulty	Status	Implementation Notes
1	Rule-based Chatbot	(E)		Use simple if-elif-else or regex pattern matching on user input.
2	Search Algorithms Lab	(E)		Implement BFS (use a queue), DFS (use a stack or recursion). A* needs a priority_queue.
3	Spam Filter (Naive Bayes)	(E)		Use scikit-learn's MultinomialNB. Tokenize text and use CountVectorizer for features.
4	Classic Game AI (Tic-Tac-Toe, Connect-4)	(M)		Implement Minimax algorithm. Connect-4 is harder and may need alpha-beta pruning.
5	Reinforcement Learning for CartPole	(M)		Use OpenAI Gym. Q-learning: discretize state space. Policy Gradient: simple NN model.
6	Genetic Algorithm for Traveling Salesman	(M)		Chromosome = path (permutation of cities). Crossover = (e.g.,) order crossover (OX). Mutation = swap two cities.
7	Handwritten Digit Classifier	(M)		Use PyTorch or TensorFlow. A simple CNN: Conv -> ReLU -> Pool -> Conv -> ReLU -> Pool -> FC -> Softmax.
8	Movie Recommender System	(M)		Collaborative: user-item matrix (e.g., SVD). Content-based: item-feature matrix (genres, actors).
9	Time-Series Forecasting Toolkit	(M)		Use statsmodels for ARIMA. prophet (by Facebook) is good. RNN/LSTM (PyTorch) for complex patterns.
10	Chat Log Sentiment Analyzer	(M)		Use a pre-trained model (e.g., VADER or Hugging Face transformers). Plot sentiment over time.
11	RL Agent for Gridworld with Hazards	(M)		Q-learning. State = (x, y). Q-table Q[s, a] stores expected reward. Negative rewards for hazards.
12	Neural Network Visual Debugger	(M)		matplotlib or seaborn to plot weight heatmaps. TensorBoard for logging loss/activations.
13	Auto Tagging for Images	(M)		Use a pre-trained vision model (e.g., ResNet, ViT) and get its class predictions.
14	Personalized Study Planner with ML	(M)		Model as regression: predict(features) -> optimal_study_interval. Features = (correct_count, last_interval).
15	Market Basket Analysis Engine	(M)		Implement Apriori or FP-Growth algorithm to find frequent itemsets. Calculate confidence/lift.
16	Autonomous Document Cleaner	(M)		Use regex for simple cleaning. pdfplumber for table extraction. Harder: ML model to classify lines (header/footer/body).
17	Document Embedding Search Engine	(H)		Use Hugging Face (e.g., sentence-transformers) to get embeddings. FAISS or Annoy for fast vector search.
18	Neural Machine Translation (Toy)	(H)		Seq2Seq model: Encoder RNN (e.g., LSTM) -> Context Vector -> Decoder RNN (LSTM). Attention mechanism is key.
19	Style Transfer Engine	(H)		Implement Gatys' paper. Load a pre-trained VGG. Optimize input image to match content (deep layers) and style (Gram matrix).
20	Face Recognition Attendance System	(H)		Use MTCNN or OpenCV for detection. Use FaceNet or ArcFace to get embeddings. Store embeddings in a DB.
21	AutoML Lite	(H)		Pipeline: scikit-learn imputers -> scalers -> models (LR, RF, SVM). Use GridSearchCV to find best combo.
22	Knowledge Graph Builder	(H)		Use spaCy for NER (entities). Use rules or a model for relation extraction (e.g., "X is-a Y"). networkx to store/viz.
23	Music Genre Classifier	(H)		Use librosa to extract features (MFCCs, spectral contrast). Train a CNN or SVM on these features.
24	Few-Shot Text Classifier	(H)		Use sentence embeddings. Classification via k-NN or cosine similarity to "prototype" embeddings.
25	Anomaly Detection in Logs	(H)		Unsupervised. TF-IDF on log messages, then clustering (DBSCAN) or Isolation Forest.
26	Question Answering over Documents	(H)		RAG part 1. Use embedding search (see #17) to find relevant docs. Feed (question, context) to QA model.
27	Vision-based Lane Detection for Driving	(H)		Use OpenCV. Canny edge detection -> Hough transform (find lines). Or, semantic segmentation (U-Net).
28	Pose Estimation Demo	(H)		Use a pre-trained model (e.g., OpenPose, MediaPipe) to get keypoints. Use keypoints to drive an app.
29	Explainable AI Dashboard	(H)		Use SHAP library. For tabular: TreeExplainer. For text/image: PartitionExplainer. Streamlit for UI.
30	Recommendation Engine for Learning Paths	(H)		Model pre-requisites as a DAG. Recommend nodes with met dependencies, ranked by user interest.
31	Text Summarization Service	(H)		Extractive: TextRank (like PageRank on sentences). Abstractive: use pre-trained T5 or BART.
32	Voice Command Recognizer	(H)		Use transformers (e.g., Wav2Vec2). For small vocab, a custom CNN on spectrograms (librosa).
33	Multi-Agent Negotiation Simulation	(H)		Agents with simple utility functions. Implement strategies (e.g., tit-for-tat, boulware).
34	OCR Pipeline	(H)		Use Tesseract (via pytesseract). Pre-processing (OpenCV to deskew/denoise) is critical.
35	Tabular Auto-Feature Engineering	(H)		Automatically create features: A+B, A-B, A*B, A/B. Use model feature importance to select best.
36	Curriculum Learning Framework	(H)		Train model on "easy" examples first, then gradually increase difficulty. Requires a "difficulty" metric.
37	News Bias Detector	(H)		Text classification. Hard part is getting a good labeled dataset (e.g., AllSides).
38	Code Review Assistant	(H)		Use transformers (e.g., CodeT5) or LLM API. Fine-tune on code diffs + review comments.
39	Knowledge Distillation Lab	(H)		Train "student" model to match "teacher" model's logits (soft labels) + ground truth (hard labels).
40	Adaptive A/B Testing Tool	(H)		Implement a multi-armed bandit (e.g., Thompson sampling) to dynamically allocate traffic to best variant.
41	AI-driven Quiz Generator	(H)		Use transformers QA model (find answer, mask it = question) or text generation model (T5).
42	LLM Prompt Optimizer	(H)		Meta-prompting. Use an LLM to generate/refine prompts. Evaluate on a small test set.
43	Active Learning Loop	(H)		Train model -> predict on unlabeled data -> select "most uncertain" samples (e.g., lowest confidence) -> label -> repeat.
44	GAN Playground	(I)		DCGAN on MNIST. Two NNs: Generator (noise -> image) and Discriminator (image -> real/fake). Tricky to train.
45	Chatbot with Tool Use	(I)		LangChain or LlamaIndex project. LLM decides which tool (API, script) to call and with what args.
46	Conversational Retrieval Augmented Generation (RAG)	(I)		RAG (#26) + chat history. Condense history + new query -> search query. Feed (history, context, query) to LLM.
47	Graph Neural Network Demo	(I)		Use PyTorch Geometric. Implement a GCN layer: aggregate neighbor messages, update node embedding.
48	Multi-Modal Search (Text + Image)	(I)		Use a pre-trained CLIP model. It maps text and images to the same embedding space. Search = vector search.
49	AI Dungeon Master	(I)		LLM for story. Hard part is state tracking: (player_inventory, world_state) must be fed back into context.
50	Agentic Coding Assistant	(I)		ReAct framework: LLM generates (Thought, Action). Action = (e.g., read_file, run_test, edit_code). Loop until done.

5. Game Development Challenges

#	Challenge	Difficulty	Status	Implementation Notes
1	Snake with Polished UX	(E)		Manage snake as a deque or list of (x, y) coords. Game state in a 2D array.
2	Breakout/Arkanoid Clone	(E)		Simple AABB (Axis-Aligned Bounding Box) collision detection. Ball velocity (vx, vy).
3	Puzzle Slider Game (15-puzzle)	(E)		Store grid in 2D array. click event swaps tile with empty space. Check for win condition.
4	Text Adventure Engine	(E)		Define rooms/items in JSON. Parser for commands ("go north", "take key").
5	Educational Math Game	(E)		Generate a + b = ? questions. Track correct/incorrect. Increase a, b as difficulty rises.
6	Typing Game	(E)		List of words. pygame or web canvas to render them falling. Check user input string match.
7	Tetris with Ghost Piece & Hold	(M)		2D array for board. Represent pieces (tetrominoes) as 4x4 matrices. Wall-kicks and rotation (SRS) are key.
8	2048 Variant	(M)		2D array. Core logic: "squash" a line (e.g., [2, 0, 2, 4] -> [4, 4, 0, 0]). Add new tiles randomly.
9	Platformer Prototype	(M)		Physics: velocity_y += gravity. AABB collision. is_on_ground flag for jumping.
10	Top-Down Shooter	(M)		Player movement (WASD). Rotate player sprite towards mouse. Spawn/move bullets. AABB for hits.
11	Turn-Based Strategy Microgame	(M)		Grid-based map. Unit class (HP, move, attack). Simple AI: move towards player, attack if in range.
12	Card Game Engine	(M)		Card class, Deck class, Player class. Game state machine for turns (draw, play, discard).
13	Physics Puzzle Game	(M)		Use a 2D physics engine (Box2D via pygame, or pymunk). Design levels as JSON.
14	Online Multiplayer Tic-Tac-Toe or Connect-4	(M)		Use WebSockets (e.g., websockets library). Server state: game_id, board, turn.
15	Tower Defense Game	(M)		Enemies follow a pre-defined path (e.g., list of waypoints). Towers scan for enemies in range.
16	Idle / Incremental Game	(M)		Core loop: currency += generators * rate. Balance upgrade costs vs. production increase.
17	Local Co-op Party Game	(M)		pygame joystick module for multiple controllers. Design simple, fast minigames.
18	Narrative Choice Game Engine	(M)		Use a graph/tree structure for dialogue. Ink or Twine are inspirations. Store game state (flags) in a dict.
19	Dungeon Map Editor	(M)		Pygame or PyQt UI. Grid of tiles. Save/load level as 2D array (JSON or CSV).
20	Racing Game with Ghost Replays	(M)		2D top-down or "Mode 7" style. Record (timestamp, x, y, angle) to a file. Replay by interpolating.
21	Infinite Runner	(M)		Player is static, obstacles move left. Procedurally spawn obstacle "chunks" off-screen.
22	Sandbox Building Game	(M)		2D grid (like Terraria). Player can add/remove tiles. Simple inventory.
23	AI Opponent Tournament Harness	(M)		Define a simple game API (e.g., make_move(board_state)). Load bots as modules and run matches.
24	Economy Balancer Tool for Games	(M)		Simulate player progression over time. Model gold_in vs gold_out. Visualize in matplotlib.
25	Dialogue Editor with Graph View	(M)		PyQt or web UI. Nodes = dialogue lines, Edges = player choices. Save as JSON/XML.
26	Co-op Puzzle Game (Two Characters)	(M)		One player (WASD), second player (Arrows). Puzzles: e.g., one stands on switch to open door for other.
27	Real-Time Strategy Pathfinding Visualizer	(M)		Use A* for single units. For groups, steering behaviors or flow fields (avoids collisions).
28	Multi-platform Input Abstraction Layer	(M)		Define abstract actions ("Jump", "Fire"). Map keyboard (K_SPACE), controller (BTN_A), touch to these actions.
29	Accessibility Toolkit for Games	(M)		UI for remapping keys. Colorblind filters (shader or color transforms). Font scaling logic.
30	Telemetry & Analytics Module for Games	(M)		Send HTTP POST requests with JSON events (player_death, level_complete) to a simple server.
31	Roguelike Dungeon Crawler	(H)		Procedural gen (e.g., random walk or BSP tree). Turn-based movement. Fog of war. Permadeath.
32	Chess Engine + UI	(H)		Move generation, legality checking. AI: Minimax + alpha-beta + evaluation function (material, position).
33	Rhythm Game Prototype	(H)		"Beatmap" file (timestamps for notes). Sync game clock with audio get_pos(). Calculate hit windows.
34	Deckbuilding Roguelite	(H)		Slay the Spire model. Procedural map. Card effects are scriptable. Relic system.
35	Stealth Game Sandbox	(H)		AI: patrol paths, vision cones (geometry), hearing radius. Alert states (patrol, suspicious, chase).
36	Isometric City Builder	(H)		Isometric grid (convert (x, y) to (x-y, (x+y)/2)). Resource management. Agent-based "needs" simulation.
37	Logic Puzzle Generator	(H)		Sudoku: generate a full board, then remove numbers. Check for unique solution (backtracking).
38	AR-based Simple Game	(H)		OpenCV + aruco markers. Find marker in camera feed, draw game elements on top.
39	Multiplayer Lobby & Matchmaking Service	(H)		Flask or FastAPI server. Endpoints: create_room, join_room, list_rooms. Use WebSockets for lobby chat.
40	Fighting Game Prototype	(H)		State machine for characters (idle, walk, attack, hitstun). Hitbox/hurtbox system. Frame data.
41	Terrain-based RTS Prototype	(H)		Unit selection (drag box). Pathfinding (A*). Simple AI (attack-move). Resource nodes.
42	AI-driven NPC Dialogue System	(H)		State-based (e.g., quest_not_started, quest_in_progress). Or, use LLM with heavily constrained prompt.
43	Metroidvania Map System	(H)		Grid-based map. Rooms "unlock" as player enters. Save bool array for room_visited.
44	Puzzle Platformer with Time Rewind	(H)		Braid-like. Store (pos, state) for last N seconds in a deque. Rewind = pop from deque, apply state.
45	Procedural Quest Generator	(H)		Use templates: "Fetch [ITEM] from [LOCATION] for [NPC]." Fill blanks from lists.
46	Card-based Programming Game	(H)		"Robot" on a grid. Cards: "Move", "Turn", "If". Player builds a "program" queue.
47	In-Game Level Sharing Platform	(H)		Client (game) needs to POST level data (JSON). Server (web) stores in DB. Client can GET list/level.
48	VR Room Escape Prototype	(I)		Godot or Unity. Requires understanding 3D math, VR input (e.g., OpenXR), and physics interactions.
49	Networked Physics Experiment	(I)		Client-side prediction and server reconciliation. Server is authoritative. Client predicts, server corrects.
50	Game Jam Engine in a Week	(I)		Focus on basics: load_sprite, draw, get_input, play_sound. Tiny, opinionated API.