Rouge Like

Basic Rouge-like, very user friendly. Point and click. No classes, but character gains specialization by what they choose to use and what armor they pick up. Can be multi-player.

Keep things simple, all hits count for "one", armor stops certain types of hits, not reduces damage. Like Hoplite (or Chrono Trigger) game is very geometric.

Not sure if I want a grid or not. If not a grid, probably click to move, with fairly slow movement (make players focus on strategy rather than timing).

This could also be turned into a space game. Warp gate to warp gate, slow ship progress

Shadows

Monsters can only spawn in shadows. Most monsters, by themselves are harmless, but groups become dangerous - archers protect meat-shields, healers so forth. Your group has to balance fighting the monsters with placing torches. There's also a balance of how spread out to be. More spread out means more light, but less support.

Flares provide a lot of illumination for a short time and can be thrown. Torches must be placed, but don't burn out.

Players have no class, but armor add skills. As do weapons.

Abstract

Inspired by [this. Everything is abstract shapes, good for graphic complexity. You can carry a limited number of abilities. Your score only counts if you finish, but then you can start again. You can gather points and power-ups, but each level gets more difficult the longer you are there.