Games and shows in space have been using these for a long time. There was a game we used to play PBEM called Stars! , that offered quite a bit for a game that was released on one floppy. It still has a rather loyal following of a few thousand players.
The way Stars! handled stargates, offered some interesting choices when designing your race, and playing.
There were a variety of stargates that could be built on a starbase. Some races had better stargate tech than others, but there were two primary factors of a stargate.
1. size of ships that could travel through it.
2. distance it could transport ships.
One particular racial super ability was that their stargates were always better. Either able to take bigger ships, or farther. depending on the tech. They were also the only race with the infinite/infinite gate.
I think for this game, it could require a planet to be donating resources to power the gate, the same way they power space docks? Lastly, they allowed for a defensive fleet (something that was always very challenging in galciv 2, in any iteration}. There could also be a rather heavy resource cost to moving a ship through a gate, if it seemed appropriate.
