I was thinking local player co-op - just for puzzle solving I think the type of game I was thinking that would make the most sense.
Core mechanic is one tall character, with higher jumps, and one shorter, with lower jumps character - both powered by a single, shared power 'unit' that you can pick up, throw, drop - so each character moves and then can throw the power unit to the other and trade off solving puzzles and escaping. So on the theme throwback you throw back the power supply to the other player. I was thinking in one player mode it worked much the same as two, except you can toggle between the character you control simply - maybe with a single button push. I have the basic tile map rendered and am just adding character movement now. It's programmer art for the moment- will be talking to the sound/art team this week.
Have you ever worked on 2d or platformers before? (or done any level design) - what I find with games like this is level design is usually where 60% to 70% of my time goes, 30% - 40% to actual programming, even more to level design if there are not to many enemy types or bosses. Bosses tend to take a lot more programming time to make them interesting. So help with both programming and level design would be great!
If you're interested why don't you grab Tiled and have a look - I'll get the code up before I goto sleep tonight on github and you can have a look and let me know what you think!
My time is somewhat limited, I have a large family and full time job (and then some) - so on these game jams I always have to thread the line between too ambitious.
You can see one game I did on itch.io for a libGDX game jam. 99 Clones - https://fivemedia.itch.io/99-clones - I'm going to steal a bit of code around the movement and collision detection from there! I did the art for that one, I hadn't met the artist yet.
- Grant