Gravitas is outstanding, and I have replayed it repeatedly even after gaining all the achievements, and here is why:

1) Its simply a great game, and I cant believe that such a great game would ever be released 100% for free

2) The NPCs will react to how you do things, like they get irritated if you ignore them and do nothing, or if you do something stupid like jumping into the pit, or get to the end of the tutorial without the gravity glove, and finding them all is just so hilarious

3) The game is so cleverly designed, and some of the levels even have multiple solutions, even going so far as one level having an achievement for doing it both the right way and the wrong way each respectively

4) The graphics and Audio are surprisingly good for an indie game, especially a free one.

5) The Developer is actively patching the games bugs even though they get no profit from this and that is more than worth respecting, and if I could find a way to support them I definitely would.

6) Its the perfect little short gem of a game to pass the time for around 15-45 minutes depending on how you play

In short, if any of these things are traits you want in a game, then this is definitely worth trying, and since it's free, it won't hurt you if you turn out not to like it anyway, although personally I hope you enjoy it since it is a great game and I think the developer needs to be more widely known given the quality of this game.