Categories in Game sound are functional at heart. You can think of them as buses. They are used for mixing purposes, and sometimes for DSP purposes. For example, if a player dives under water you may want some of the sounds of the game to change (i.e. pitched down, EQed, etc). But some sounds should remain intact (UI sounds, some dialog that needs to be understood). Categories are used to accomplish this.
The construction of categories will follow the needs of the game. Generally at the top the categories are the same as film. Dialog, Music, FX. This allows for the sliders you see in most game option menus that lets the player lower or remove sound. But sub-categories are very important. For example, in most games some dialog is important enough that the rest of the mix is ducked so the line can be heard better (mission critical dialog, dramatic dialog). Other lines are not (chatter). Usually that is reflected in dialog sub-categories: critical, non-critical. the same may be true for particularly important SFX sequences. If you have destroyed the Eiffel Tower during a fire fight, it might be nice to lower the sound of the chattering machine gun right next to you so you can hear the groaning metal of the giant structure collapsing around you. Again, categories are used to accomplish this.
Hope this helps