FPS Engine

A small, understandable custom game engine in C++23, and an online multiplayer first-person shooter built on top of it. Authoritative dedicated server, client-side prediction, snapshot interpolation.

This is not an attempt at a general-purpose AAA engine. Every system exists because the FPS needs it.

Layout

engine/   Reusable engine library (no game-specific code)
game/     The FPS: shared simulation code, client, dedicated server
tests/    Unit tests (Catch2)
docs/     Architecture, networking, milestones, decision records
cmake/    Build helper modules

Build

Requires CMake ≥ 3.25 and a C++23 compiler (AppleClang 15+, GCC 13+, MSVC 2022).

cmake --preset debug
cmake --build --preset debug --parallel
ctest --preset debug

Binaries land in build/debug/game/: fps_client and fps_server.

See docs/build.md for presets, sanitizers, and CI details.

Status

All milestones (M0–M10) complete — playable online deathmatch with an authoritative dedicated server, client-side prediction + reconciliation, snapshot interpolation, and server-side lag compensation. See docs/milestones.md.

Play

./build/debug/game/fps_server --port 7777         # dedicated server
./build/debug/game/fps_client                     # menu -> Connect / Practice

Client flags for testing: --connect <ip> --name <n> --fake-latency <ms> --fake-jitter <ms> --fake-loss <pct> --no-vsync --run-seconds <s>. scripts/package.sh stages a distributable zip (binaries + assets).