A very blatant copy of Portal. Level 0803 literally exists in Portal 2, and every cube or interactable object is from Portal, except for the bridge. However, the non-carryable version of it exists in Portal 2 under the name 'Hard Light Bridge.

After almost 3 hours of playtime comprised mostly of walking around or actually executing puzzle solutions (not thinking about how to solve them or trying solutions, just executing the first thing that came to mind), I had completed 6/15 chapters. Based off the demo, I expected to be occasionally challenged. Although the premise of rewinding time on certain objects to solve puzzles could be used so many interesting puzzles, I'm not exaggerating when I say there were only two puzzles I encountered that made me think for more than two minutes, and one of those managed that only because I was exhausted--I solved it immediately upon waking up the next day.
At the time I put the game down, the newest mechanics were the river and the enemies, which were annoying at best. The rivers instakill you if you get anywhere near close, killing you and resetting any puzzle elements (this is a puzzle game with rewinding as a core mechanic, why couldn't they have just rewound you???). Getting close is a required part of one of the first puzzles involving the river. The enemies require you to run around them, countering them by rewinding their projectiles in midair, which requires fast reaction times and way more precision than anything in the rest of the game -- totally out of genre in a bad way.
Either they chopped off the best puzzles for the demo, or they decided that they should put any and all good puzzles in the latter 60% of the game. I was not motivated to find out, either by the annoying story (which I muted about 10 minutes in), the atmosphere, or the puzzles. You're better off playing Portal community levels. Thank god for Steam refunds.

Portal without Polish.

If you have never played Portal, you might enjoy this. Otherwise this is B O R I N G. Five chapters in and I'm still doing the same things in the puzzles... Place your item in reverse order. Move to first location. Press reverse button. Move to next puzzle. Repeat. (edit: Chapter 6 had two puzzles where I had to think... Is there hope?, Edit2: Chapter 7 and 8 had a few more decent puzzles, but some really annoying check points. )

Actually, if you have never played Portal or especially Portal 2. What are you waiting for? Skip this and play those.