I honestly enjoyed most of this game, which is why giving it a negative review bites. The problem is, the back chunk of the game is atrocious. You're suddenly going from what I referred to a couple of friends as "Hard-Mode Portal" (same 'solve the puzzle room' gameplay, with two-button controls, even if it's opposing magnetic polarities rather than holes in time/space) into a terrible action title.
I was going to recommend this with a caveat of "By the end, some puzzles become irritating due to the checkpoint system, where you may have to restart chunks of stage if you mistime a polarity swap or make a slight field mistake on some items", but no, when you suddenly have to begin juggling explosives to kill massive sahaguin and all sorts of tentacled beasties* whereas you were previously free to take time and puzzle things out? Ick. The final stages are the worst: one involves distracting and repeatedly-bombing a behemoth to reach an entrance within sight, and then the finale is an irritation because it combines waiting for enemy patterns with dodging instadeath and making precarious platforming leaps.
If you wanted an unpolished puzzle game, the first half or so is solid with little to no hand-holding (so it's got some brain-teasers for some of us). The latter bits, though? No. Nope no good no siree.
* I only mention this because while I was blind to the latter half of the game going all Cthulhu, I'm told the marketing heavily sold it as such? Either way, multiple people assured me it wasn't the spoiler I assumed.