Here are some ideas for the game.
- Tools
- Pushable block. Can be pushed around to serve as a stepping stone to access a previously inaccessible location. Can only be pushed horizontally or made to fall downwards.
- Dynamite. Explodes bomberman style, in a grid-based pattern, for predictable damage. Keeping effects predictable to the player is important for a puzzle game.
- Tunnel bore machine. When placed, this machine would drill straight through rock until it meets either air or unbreakble rock. Might be an opportunity for a cool animation but its usability as a puzzling mechanic would likely be limited.
- Placeable ladder. Very similar to pushable blocks in purpose, but subtly different. Crucially, the player is able to carry this thing up a ladder. It actually supersedes the pushable block in usability in almost very way, except that a pushable block is reusable whereas a placeable ladder is not.
- Water streams or balloons to move tools or blocks. Since you cannot jump while carrying a tool, transporting tools to a different location via balloon or water stream could be an essential puzzling element.
- Rocket boots, jetpack or car that, if used on a sufficiently long straight track, will exceed 88 MPH and travel through time, delivering the player to a different section of the level. If you do not include this in the game, you're clearly chicken, McFly.
- Other
- Trap that flings knife? More generically; tripwires or pressure plates that are activated by the player and that may trigger a variety of effects.
- Pockets of natural gas that will explode if you create a spark (IE use a tool) or use fire or explosives nearby. You could perhaps use this to set up elaborate chain reactions. As always, it is important that the player is able to predict exactly what the results of his actions are going to be. Explosions must be predictable in how they are triggered and what damage they cause.