Ravenfield

Ravenfield from solo developer SteelRaven7 is the spiritual heir to Battlefield 1942's bot-stuffed sandbox mode — easy to pick up, surprisingly deep once you start tweaking, and completely shameless about being silly. You and a swarm of Blue AI allies fight a swarm of Red AI enemies across maps that scale with your hardware (the only practical limit on combatant count is what your CPU can handle). Tanks, helicopters, jets, watercraft, infantry — pick what you want and just go.

The active ragdoll physics is what made Ravenfield a meme — soldiers fold in unintentionally hilarious ways when they take a tank shell, and the team-colored blood splat system means you can see where the firefights happened on the map. There's a thriving Steam Workshop community of fan-made vehicles, weapons, and maps; the Conquest mode is the highlight.

Released as OFME, fully offline-playable. 543 MB installed. Multiplayer between cracked clients works via the Online-Fix mod's relay (peer-to-peer); no Steam account needed for hosting or joining.