Kongregate a go. "Thomas was alone" was made by Blitz Games Studios designer Mike Bithell on October 16th and 17th, during a span of just 24 hours. As Bithell notes, "I went from blank screen to decent puzzle platformer in less time than it takes Jack Bauer to save the world. That's a pretty cool achievement."
Thomas was alone is part minimalist platformer, part geometric buddy road-trip. Things get interesting once Thomas encounters his first friend, a dull, prim-and-proper Puritan and all-around square. Also, he's literally a square. By taking control of different pals and taking advantage of their unique dimensions, you'll be able to solve simple platforming challenges and progress. Describing it as a block-stacking game is accurate, albeit unimaginative.
We've enjoyed one of Mike Bithell's games before (surely you remember Visiting Day from 2006?), and while this one's bothered by slippery controls, it's an effective reminder of how simple, immediately decipherable mechanics form the basis of any worthwhile game, regardless of the presentation. The impressive 24-hour construction period is also motivational to any budding designers out there. Why, just look what Blitz Games Studios has to say on the matter:
"The games you make don't have to be epic masterpieces, they don't need to make use of bleeding edge graphics. A little bit of heart and a simple idea can go a long way. Frankly though, if Mike can manage it, so can you!"