Neon Metro 2099 takes the .io formula underground, dropping you into a glowing metro of a future city where everyone in the lobby is a rival. The genre's pleasures are all here: a live shared arena, the constant read on who is bigger and who is bluffing, and the risk-reward math of chasing another player versus keeping your distance. It loads free in the browser with no download.

What sets an .io game apart is that the difficulty is other people, and the neon-metro setting gives that scramble a moody backdrop to play out against. Runs stay short and restarts are instant, so a bad wipe just means straight back into the fray. When you want the same competitive buzz, there are more io games in the collection.