Actually, there were a lot more good and interesting ideas, when our team (there are four of us) started to think about concepts. There were thought based on a music genre "Vaporwave", idea about wax-man, who can melt on the sun, moreover - cooling systems tycoon :D. We tried to imagine as many interesting varients, as possible.
This exact idea was based on a simple contrast of heat and cold + an idea, that sun can give you a shadow. Quite ordinary thing in a heatwave to choose a way in a shadow to feel less heat. Then it was some vibes from playing FEZ - so we came up with a thought - what if it would be a 3d puzzle game, with rotaiting shadow to pass through some hot space (in FEZ you "rotate" the world to find a way).
This idea was the most straight-forward, i guess that's why we finally choosed it. Simple ideas are suitable for jam C: