Making FPS Mods
Part 1: Mod Types
There are only three mod types, no more, no less. Forget trying to make something "innovative", as nothing original ever makes it out of the starting gates. While the three main mod categories exist, you cannot make a mod which is outside of their horizon dominating range, because absolutely nobody will play it and you'll look like a fool.
The three mod types are:
Class Based Mods
If you were to look at the most popular mods being played at any time, chances are that 98% of the servers out there will be running one of those three types of mods. If you find them running a different mod, it more than likely is a server error or misreporting bug. You should think about contacting the guy who runs the server to let him know.
Once you've decided what mod you want, you'll need...
Part 2: The Name
The categories each have well defined naming schemes that you should stick to, under penalty of being chastised by the entire gaming community. It's best to use one of the below words for whichever category you intend to mod, look it up in a thesaurus, then put on a blindfold and randomly choose a listed word.
For a Weapons mod, use "Armageddon" or "Havoc". Try to play the sheer "chaos" factor up as much as possible, because Lord knows, everybody loves a game where you die the second upon spawning.
For a Class Based mod use "Team" or "Rely on better players to win for you". Teamplay mods are quite popular despite the fact that people playing the mods hardly ever work as a team. In any given team-based mod, there will either be 95% of the team on offense or 95% of the team on defense. This is teamwork!For a Counterstrike based mod, just add on the name of the game you intend to port Counterstrike to (e.g. Counterstrike UT, Counterstrike Q3a, Counterstrike DH3) or if you don't have permission to use the Counterstrike name, use something to do with terrorism or policing or some hideously long and obscure random set of letters chained together, e.g "U.N.M.A.T.S.A.D.L.P.C" ("Uzi 9mm Anti-Terrorism Strategic Annihilation of Dolph Lundgren's Presidential Campaign"). Try to reference the fact that the world is in danger and only the player's elite team of lagged snipers can save a plane from being hijacked or the President's daughter from being kidnapped or whatever the hell your "realistic" goals are.