Mine gets a little warm when I play Solitaire so I imagine it will get pretty warm if your playing an processor intense game.
Processor management is the real deal.
Very simple games sometimes use a lot of CPU because they are poorly coded. Kind of binary: 0% of CPU or 100% of CPU. Typically chess games. In easy mode, once the computer is doing a move, it uses 100% of the CPU. When it is your turn to play, the computer uses 0%. In hard/pro mode, the computer is always using 100% of the CPU, even if it is not his turn to play. Why ? Because it is "predicting" your next 1000000 possible moves and which strategy it has to use for each move, and bla bla bla. As a consequence, after 2 minutes, your device is hot like crazy, for no real reason.
But not all the games are like that. Some are very well coded and use the right amount of CPU only when needed.
Another "not perfectly" coded game is Microsoft Jigsaw Puzzle. Makes my device hot for no reason.