Great game! I'm a sucker for atmospheric puzzle games, so I really enjoyed my time with this one!
My favourite level was easily the 3rd one (The one with the levers, I did them out of order so I may be mixing them up!). I wasn't a huge fan of the first two levels where you essentially just try to walk to the end, but I was intrigued enough by the premise of summoning whatever the heck I was summoning to power through it.
I do feel like the summoning theme was used very loosely here. I didn't really understand how my actions were directly contributing to the summoning of the colossus, and I was a bit disappointed that I didn't get to actually see it at the end. The theme almost felt like an after thought.
All in all, I'd love to actually see more of this! I feel like there's an interesting story to tell here, and I hope you have plans to continue with the project past the jam!