Well, I made some progress so far. My idea is that every coin you collect makes you slower, but you need them to buy things in the shop after the levels. You can throw them away to get more agile, but then you have less coins to spend. Tricky. So far I got a raw engine working, now starts the work on that sweet sweet grappling hook, because... grappling hook. Also here is a random GIF from my amazing test room.