Overview Cogs HD is based upon the PC game Cogs, and you can read all about it in our review of the iPhone version . Features The iPad version is practically a direct port of the PC version giving you fifty levels of sliding puzzle fun to arrange pipes and gears. The game is native iPad resolution which is nearly the resolution it runs at on the PC rather than scaled down like the iPhone version. Each platform it runs on Cogs gives you 50 levels in inventor mode, and then in challenge mode you play those same fifty levels, but have a goal in completing them in a certain time or number of moves