Puzzle maze games are more my thing, so in the vein of "Press 5", here's my mockup.
You have to navigate the little treasure-loving-ninja-gnome through the maze, while he just walks and auto-turns right when he hits a wall, you push five to spin the floor 90 degrees clockwise to navigate him elsewhere. Collect treasure for points and have to find a set amount of keys to get out and on to the next level. Avoid traps and enemies but there are some squares on the ground that auto-dictate what happens--like those arrows, when your sprite hits it, he automatically goes the way its pointing (but so do the enemies so if they hit a square that activates a bomb you better navigate outta there before it counts down to zero). Later there will be actual blocks that can do things to the level (like slide across the floor tiles to hit things/set off traps/etc). I'm thinking boss stages too where you get bonus points depending on how quick you deal with it and super treasure. (And since you can't attack, you need to navigate the little guy over squares that'll help you out in those cases).
I'm thinking it's what happens when you mutate ChuChu Rocket with Druaga. I've also got an idea for multiplayer (up to 4 players) that deals with sabotage and treasure collecting.
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Schu