Use the arrow keys to move. You need to collect all the coins to open the next level portal. This took a really long time to code (for me). Press See Inside if you don't believe me. Level 1 and 3 are pretty hard.
Credit to @griffpatch for the tutorial on YouTube. Credit to @princess12321 for testing my game. I really have no idea why I called it portal a platformer. If someone completes this in mobile mode, please comment that you did it because i am yet to know if it is possible without a computer.