I would recommend playing the original instead. The endgame is hard as hell for the worst reasons. Screw up a few missions and ypur rep will drop so low you won't have enough funding to carry on. Fail to capture specific aliens and technologies and you won't be able to construct the ship that can take you to the final boss. On top of that, research bugs might make it impossible to reach the end of the game at all. There was a tool for patching the research bug when it occurs, but the site where it was hosted seems to be net dead(correct me if I am wrong.). And you seriously need keep recruiting new blood to find high mental abilities on your soldiers lategame OR you will get totally wiped out by your own brainwashed/berserked troopers. But I guess the same is true for the original X-COM. Oh, and the game physics don't behave like it's underwater at all.
