Survev.io

Survev.io is one of those games that respects your time: open the page, hit play, and you're playing within seconds. It's an arena of real players, which means the difficulty is human: unpredictable, occasionally ruthless, always beatable.

It's played with keyboard and mouse, so there's no setup beyond your hands and the screen. Phone, tablet or desktop, it runs the same, so you can pick up where boredom finds you. Fullscreen mode is there when a browser tab starts feeling too small for the occasion. Nothing to lose but the next half hour.