Beat the game. It was actually a well designed game. Very basic little puzzle. Fun to play. And did not overstay it's welcome.

It terms of improvement. I was uncertain how collecting coins was connected to the portal. I would certainly say that communicating the coin requirements would help in learning the mechanic early on. Eg. The portal could count up visually (or with text) as you collect the coins. Change visual state when all coins have been collected.

The mechanic itself did not change much over the game. Think of ways to modify the mechanic over time with other elements to increase variety.

Good luck with your future games.