Really cool ideas here, especially for a first game jam. The time dilation mech is a strong hook, and you used it well in the level design. The puzzles were actually thoughtful; platformer design usually stumps me, so the fact that I was engaged instead of frustrated says a lot.
The particle effects looked great, too. That big combined one at the end was especially nice; you can tell you put real time into polishing that moment. Totally worth the 10-15 hours. Also, major respect for doing all the art and audio yourself. Everything felt consistent stylistically.