We just shipped a big change to SweatyPanzer, our browser WW2 tank shooter: the main mode went from round-based 4v4 to Arena, an endless free-for-all. Full devlog: Arena: a new free-for-all mode.

A few design problems we had to solve along the way:

• Snowballing. Every kill gives a card draw (an upgrade or another tank), so a good player gets stronger fast. Our answer is the bounty: after 10 draws in one life you are marked for everyone and have 4 minutes to survive. Survive and you bank XP, but your upgrades reset.
• Endless but not stale. The map changes every 6 minutes and you keep your tank, upgrades and kills across the change. Every map is played once before any repeats.
• Bots that feel like players. Bots go for targets they can beat, back away from stronger tanks while firing, and join fights nearby instead of all hunting one player.
• First games. New players start in a rookie Arena game with half-strength bots for one map, then move to the full Arena.

Happy to talk about any of it. It is free to play in the browser (WebGPU, so current Chrome or Edge on desktop).