I came up with an idea for players to use a command like "votegametype" or something and they get to choose from whatever the server has. E.g. I have gg_deathmatch, gg_elimination and gg_knives_only on my server, a menu will come up asking which one to vote for:
1. Elimination
2. Deathmatch <Current>*
3. Knives Only
4. Don't Change
*The possibility to state which is the current gungame type.
And maybe, on every map change, it goes back to the server default?
I was going to attempt to code it myself, but after looking at some of the .py files, I got lost and the whole menu handling stuff threw me off.