I can't unlock level 4...

[BardmanJ]

I've combed almost every level, looking for secrets and i still cant find a way to get the level 4 portal open. Is this a glitch and I just stupid?

[Seamus]

You just missed a key somewhere.

[one_irish_giant]

Check the stand in front of the portal to see if you're missing any keys (I'm sure you are). After that, go back and look at the ground in front of the portals for levels 2 and 3. There will be markers on the ground that will light up once you have found the keys/chrono pieces in that level. Find the portal that has a marker that's not lit up.

[one_irish_giant]

Pretty sure I know which one you're missing too, because it's the one I used to miss a lot as a kid.

[allthevideogames]

https://steamcommunity.com/sharedfiles/filedetails/?id=630675000