GTA SA GETS PRETTY HOT on IPHONE 5s?

My iPhone 5s gets hot playing GTA SA pretty quickly after start up of game. In about a minute in to the game the back and the sides are pretty hot but can still be held in hand. Has a Anyone noticed this on there 5s or 5 I'm really wondering if it is normal so please if you notice this type below
Or just what happens to your particular device when you play it put it below thank you so much for your replies.

Since the game is big, it takes off the RAM of the phone… So the phone will start to process too much of data… Before starting the game… Just closes the ongoing apps/games then play the GTA game. Will help you…

The heat that you're feeling is typical of all smartphone users playing graphically intensive games.

Let me explain in basic layman's terms. When you play a game, your phone automatically kicks into full gear mode, using the full clock speed of your phone's CPU and GPU. Since your phone is running at the max clock speed, it will generate heat. Since your phone doesn't have an internal fan inside it, heat will definitely be noticeable. Say hi to SCIENCE! Have a good day.

To the person who said that RAM plays a factor in heat generation, you're very incorrect. What the RAM on a smartphone is supposed to do is manage a lot of the system activities. Devote some resources to apps, which is how the phone stays smooth. The less RAM, then the harder it is for a phone to stay smooth.

However, since you're playing a game that's pretty graphically intensive like SA, it means that your phone will be running at full clock speed. This means that the CPU is running at the max capability, which will generate a lot of heat (as I explained).