Survivor.io

One thumb is the whole control scheme, and that turns out to be plenty, because Survivor.io throws more than a thousand monsters at you at once. The city has fallen to a zombie outbreak, you are one of the survivors still standing, and each run drops you into a map that fills up fast and keeps filling.

You move; your weapons handle the rest. Kills drop experience, levels arrive quickly, and every level offers a choice of skills — new weapons, upgrades, passives — that stack into a build for that run alone. That roguelite layer is the heart of it: a setup that melts crowds early can fall apart against the late waves, and a strange combination you picked on a whim can carry the whole stage. No two runs quite repeat.

Stages vary in layout and difficulty, bosses included, and the pressure curve is the pleasure: the first minutes feel manageable, the last ones are a wall of bodies with you surfing the gaps. It is built for short sessions and one-handed play on the move, and the bright, clean art keeps the chaos readable even when the screen is mostly zombies.

If you like horde-survival games trimmed for phones — quick runs, big numbers, builds to experiment with — Survivor.io is the polished, pick-up-and-play version of the idea.