Turn-based Auto-battling Experiments

This is a toy project for experimenting with game strategies in a turn-based combat, akin to fights in role-playing games like Might & Magic 3/4/5, Eye of the Beholder, Bard's Tale, etc.

... with the twist of having ✨Artificial✨Intelligence✨ select your turns.

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This is definitely not rocket science being done here. Expect more minimax than AlphaZero.

Example outcome

The following is an example of how it may unfold.

We see the hero party, consisting of Brull, as well as the enemy party, consisting of Ziuon and Molphige. Ziuon deals only 5 damage with their stick, but Molphige deals 20 with their fists, which will take Brull out in one hit. Regardless of Molphige being the third one to move, the only viable option is for Brull to attack Molphige first to ensure they can never make a move to begin with.

That is indeed what happens:

Performed 921 evaluations with 221 cuts at depth 8 in 309.766µs. The encounter has 5 turns.
TL;DR: The initiating party wins with a score of 10.

On the attacking side:
- Brull, with 20 health and their fists (10 damage)

On the defending side:
- Ziuon, with 15 health and a stick (5 damage)
- Molphige, with 10 health and their fists (20 damage)

Turn 1 (discovered at step 1):
  Brull whacks Molphige with their fists, dealing 10 damage
   ⇒ Molphige has given up on being alive

Turn 2 (discovered at step 2):
  Ziuon whacks Brull with a stick, dealing 5 damage
   ⇒ Brull now has 15 health

Turn 3 (discovered at step 3):
  Brull whacks Ziuon with their fists, dealing 10 damage
   ⇒ Ziuon now has 5 health

Turn 4 (discovered at step 4):
  Ziuon whacks Brull with a stick, dealing 5 damage
   ⇒ Brull now has 10 health

Turn 5 (discovered at step 5):
  Brull whacks Ziuon with their fists, dealing 10 damage
   ⇒ Ziuon has given up on being alive

If retreats are allowed for the enemy party, the game has a different outcome: The enemy now decides to flee at their first chance. The hero party still gets an extra move, but it is not enough to result in a defeat of the enemy.

Performed 1063 evaluations with 247 cuts at depth 8 in 360.599µs. The encounter has 3 turns.
TL;DR: The initiating party let the opponent flee with a score of 2.

On the attacking side:
- Brull, with 20 health and their fists (10 damage)

On the defending side:
- Ziuon, with 15 health and a stick (5 damage)
- Molphige, with 10 health and their fists (20 damage)

Turn 1 (discovered at step 1):
  Brull whacks Molphige with their fists, dealing 10 damage
   ⇒ Molphige has given up on being alive

Turn 2 (discovered at step 2):
  the party flees

Turn 3 (discovered at step 3):
  Brull whacks Ziuon with their fists, dealing 10 damage
   ⇒ Ziuon now has 5 health

Rules of Engagement the Game

• Two factions are fighting each other and take turns in making moves.
• Within each faction, a party of one or more participants is allowed to make a move. Such an action can be,
  • Attacking a single opponent,
  • Attacking a group of opponents (area effects),
  • Applying an effect to a party member,
  • Skip the turn, i.e. do nothing.
• In addition, the faction as a whole can flee.
  • If a faction flees, the opposing faction gets one last turn.
• Party members can panic and either flee, be paralyzed or attack their own faction.

As for actions,

• Some actions are instantaneous (attacking an enemy),
• Some actions take preparation (e.g. preparing a magic spell),
• Some actions have requirements (e.g. a potion must exist to be used)

Things to do

• Regular minimax (src/solver.rs).
• Multiple turns per party (src/action_iterator.rs).
• Implement Alpha-Beta pruning (src/value.rs).
• Implement Iterative Deepening.
• Implement A*-like heuristics.