Save this for tomorrow at the office
While Ending might initially look needlessly abstract, its design is anything but. It's one of those upper-tier puzzlers that requires no real explanation going in -- you just start the game, and learning is built into the intuitive design and pacing of levels. I tend to get frustrated easily in this genre, but that wasn't the case here. Someone did their homework.
Beyond the individual puzzles that are offered on a room-by-room basis, Ending has a larger, procedurally-generated level that continuously opens up so long as you aren't destroyed by its many threats. Not my cup of tea, but I have a feeling some of you will get significantly more enjoyment out of it than you will from the core levels.
How much does it cost? Nothing. Well, that depends. Ending is free if you're playing from a browser or grab a desktop build for Windows, Linux, or Mac. There are also iOS and Android versions of the game available for a buck each. Super reasonable.