Hexic HD is a solid puzzler that is very addicting, but I probably wouldn't have bought it if they didn't give it to me.
There are three modes in the game, marathon mode, timed mode, and survival mode, all of which have their own specific achievements. Marathon mode is fun, but when a bomb comes in when you have a lot of points and you've spent thirty minutes earning them, it is very frustrating to not find a match. Timed mode is basically the same as marathon mode, but obviously you are timed. Time isn't a very big factor since everytime you get a match your time goes up a few seconds. Survival mode is not very different either. You find all the possible matches then the ones that didn't match are frozen and you have to unfreeze them by matching them with the same color. Overall Hexic HD is fun and entertaining for a while, but don't count on it to be your favorite Xbox 360 game.