Have You Played? is an endless stream of game recommendations. One a day, every day of the year, perhaps for all time.
This is a game that has time travel that requires you to think along the same lines as amazing time travel move Primer. Like this. As well as Portal, and any number of other classic puzzlers, all put into one smart, and extremely accessible game. And most remarkably of all, it's all in a 2D side-scrolling platformer.
The joy of the game is uncovering the new mechanics for yourself, so you should just darned well get hold of it and explore. It's charming at the same time as challenging, which makes a big difference, and you'll be rather in awe of the brain inside the head of its creator. Not one to overlook.