The game was excellent.
Very good enemy roster with Ancient caves being the apotheosis on that front, each area is unique enough, a cool and organic puzzle or secret here and there, music is nice, gfx are sometimes simple but always clean, diverse and inspiring enough, the game is big, difficulty is on point with, in particular, always the right length of sequences between two save points, I like that several sequences are just as hard as boss fights instead of the difficulty being restriced to boss fights.
I guess even the 5 seconds of dialogs before fighting a boss could be skippable so you can retry quicker, and a matter of taste but the best parts being the hard area you can access early but will probably not manage to beat right away, like this one in Electric city, I sometimes felt the game could be even slightly more nonlinear.
Anyway, I loved every second of the game, thanks for sharing, I'll follow whatever you'll come with next in the case you intend to release more games.