Relicta

An interesting but flawed game based around Portal-like puzzles that rapidly ramp up in complexity and become multi-part epics long before you're even close to the end. The balance between puzzles and the story throughout is a double-edged sword: on the one hand, this balance is not handled very well, with the story almost becoming a distraction when it's inserted in brief but dense chunks of dialogue interspersed between the increasingly lengthy puzzles. However, as the free campaigns included with the game in the last update demonstrate, if you remove the story completely, which is also told in the main game during longer spaceship sections between each area, then working through puzzle after puzzle with no respite becomes too much of a chore (though granted, these campaigns do also bump the complexity of the puzzles up even further to an absolutely exhausting degree). The story then, somewhat paradoxically, is what makes the game more successful than not: it's a sincere attempt at providing a human and emotional element to an otherwise totally abstract game, and it gives you the motivation to keep pushing further onwards.