Blocky platformer game tileset is a tileset which is NOT seamless.
But it designed carefully to make it looks good despite of the blocky nature.

Spaceship Area Game Tileset.
A set of seamless 2D game level set.

Factory Area Tileset.
A set of seamless 2D game level set.

Lava Cave Area Game Tileset.
A set of seamless 2D game level set.

Rocky Cave Area Game Tileset.
A set of seamless 2D game leve set.