Bullet Force is one of the most complete first-person shooters that runs in a browser. Lucas Wilde built it as a modern military shooter — loadouts, attachments, camos, killstreaks — with team deathmatch, conquest, gun game and free-for-all modes across a set of proper multiplayer maps.
It plays much closer to a console shooter than most browser games manage, which is why it has stayed popular for years. There are bots to practise against and real lobbies when you want them.
Yes — it runs free in the browser with no download. There are optional purchases in the standalone versions, but the browser game is fully playable without them.
Yes, with team deathmatch, conquest, gun game and free-for-all, plus bot matches for practice.
Yes, with nothing to install — it is one of the heavier browser shooters, so close other tabs and lower the graphics on older hardware.