70°C for the CPU temp is "normal" when you paly a game. Remember that we have a quadcore at 2,26Ghz without any cooling system...
In any case there is the thermal trottling to prevent any damage. According to the CPU temp (and also the battery temp) the CPU freq decreases automatically.
Also there is an hotplug routine according to the temp (cores offline at a certain temp).
The last "ultimate" thermal protection is the shutdown at something like 100°C (according to the thermal-engine.conf file it "should" be above 100°C, but...).
So no worries there is a protection and your CPU temp is not abnormal.
One among the others: http://forum.xda-developers.com/show....php?t=2597508