Co-op
Brotato 1.1.15.4 co-op takes up to 4 players (2 on Switch). Each extra player adds 30% more enemies, 30% more enemy HP and 8% more enemy damage, and every enemy drops more materials: with two players the waves hold ×1.69 the HP and each player gets about 93% of a solo run's materials. A run is lost only when every player is down in the same wave. Best duo in 1953 simulated pairs: Brawler + Jack (100% of Nightmare runs won).
How co-op scales
| Players | Enemies | Enemy HP | Total HP to clear | Enemy damage | Materials per enemy | Materials per player* |
|---|---|---|---|---|---|---|
| 1 | ×1.00 | ×1.00 | ×1.00 | ×1.00 | ×1.00 | 100% |
| 2 | ×1.30 | ×1.30 | ×1.69 | ×1.08 | ×1.43 | 93% |
| 3 | ×1.60 | ×1.60 | ×2.56 | ×1.16 | ×1.70 | 91% |
| 4 | ×1.90 | ×1.90 | ×3.61 | ×1.24 | ×1.88 | 89% |
* if the players pick up evenly; each material goes to whoever picks it up.
How this is worked out
CoopService (coop_service.tscn): additional_enemies_per_coop_player 0.3, additional_enemy_health_per_coop_player 0.3, additional_enemy_damage_per_coop_player 0.08; materials per enemy × (1 + ((n ÷ enemies − 1) ÷ (n − 1)) × 0.8 × (n − 1)) — get_coop_materials_factor; enemy count in EntitySpawner, HP and damage in EntityService.
Each player has their own…
shop, materials, XP and level-ups, items and weapons. A material counts for the player who picks it up.
Going down
The wave is lost only when every player is down; the run ends then. Until that, the others keep playing.
Danger and endless
Danger levels and endless scale on top of the co-op numbers, the same as solo.
Best two-player combos
Every pair of characters, each starting with its best solo weapon, 60 simulated runs on Danger 5 and on Nightmare; the best 300-run pairs again. Ranked by Nightmare wins, then Danger 5.
Best partner for each character
How the co-op simulation works
Two players share each wave of the game's wave files with the co-op scaling above. Their damage is pooled to clear the wave; each takes half of the hits the wave lands (more when the pair is too slow to clear it). A player whose hits exceed what they can take goes down for the rest of that wave and earns nothing from it; the run ends when both are down in the same wave. Each player then shops and levels on their own, as in the solo simulation.