Blackshift

Blackshift is an action puzzle game with over 100 carefully crafted levels full of mysteries and danger. 
New items and mechanics are introduced steadily throughout the entire game, with almost every level containing something you haven't seen before.
Secrets and hidden paths abound; if you stray from the main path and thoroughly investigate, there are hidden things to discover on each level, as well as secret levels to find.

Testimonials for Blackshift

I've played a lot of puzzle games before, but it's been a very long time since I've been this enthralled by one! — Jasmine_Steel

I could not think of a better puzzle game. — dr omsk

If you like solving mazes with different mechanics, this is for you! It's challenging enough to keep you thinking, and with new mechanics the further in you go, it doesn't get stale. — Ashman The Guy

A true hidden gem. — randomized0000

As far as Chip's Challenge like puzzle games go, Blackshift is probably the strongest one I've played. — Asp

If you've never heard of it, but like puzzle/platformers, this is one of the best. — peterbres

I had so much fun playing this, feels like it was made for me. Uncountable mechanics, surprises, secrets, different ways to play. — Novato Zotto

Best puzzle game on Steam! — Ubu

(All quotes from Steam reviews)

The Level Pit

Make your own levels with the built-in level editor, and upload them to the Level Pit where other people can play them. There are thousands of user-created levels in the Pit, each with its own leaderboard. You can even watch replays of other people playing your levels. The Editor and the Pit are both built into the game; you can do everything from within Blackshift itself.