The only difference between SSD and HDD for games is loading times. SSD is faster than HDD. SSD is more expensive than HDD, so people usually have an SSD as their boot drive and an HDD as storage.
The only time storage device speed affects games FPS is when you don't have enough physical memory (RAM) to hold the game data after it loads. If the game data is more than your RAM can contain, the remainder is loaded onto disk. In windows they call this virutal memory AKA paging AKA Swap. While paging, games slow down quite a bit, so you need to have enough RAM. If you have 4GB+ memory in your PC, you are probably OK.