This is a very large 'design' for a good RPG styled gamemode, and actually, any mode i guess since they are all build in. I have absolutely no idea if its possible or not, but i am confident this team is able to create the best GTA experience ever (perhaps without even looking at my idea's), but i had time so here is my perfect view of a RPG-GTA-World..
Team's
Red -- Some Fancy Gangname - - HomeBase LS
Blue -- Some Fancy Gangname -- HomeBase SF
Green --Some Fancy Gangname -- HomeBase LV
Solo -- No 'Gangname' -- No Homebase, Spawnpoint all small villages too choose from
Police -- For some reason this is not a logical choice, it should be NPC's IF there can be police, it would be alot of fun to pop some cops with your mates. Playng as a cop gives you huge advantages (heavy vehicles, npc allies(?), and just, ur the law, i doubt anyone would obey it tho) So, Human Police is fun, but only joinable as police Admin.
Each 'Team' can spawn on their own Island at their own homebase. At the homebase special ability's like the CarSpawning system can be done. You can join a team by being accepted by the teamleader. If you aint being accepted you can get in by more then 50% of YES votes from that gang. You can also go solo, but you cannot take a class, only the 'All-Round' class and will spawn in one of the little villages. You'll will BE see-able on the map, so you make good target practice for the team's.. watch out.
Each gangbase CAN be attacked by another Gang, only each gangbase has stational miniguns (Like zero's RC Shooting Mission) to rifle down any attacker. When another gang takes the homebase (Get to the spawnpoint in the gangbase and keep it for 3 minutes) the gangbase shall be taken and the takens gang can spawn somewhere else in their own city to try and take back their Base. The takentimer is on 15 minutes, if a gang is without base for 15 minutes the atacking gangattackers in their base will be teleported to their own homebase and the own gang can spawn again there, having back their base.
Player Type (With Unique Names In Each Team, Same Abilities and Weapons)
Gunman -- Uzi, Mp5, Ak-47 a/o Fancy MachineGunz -- 'Hitman'-Skilled, Ability to Shoot out Of Windows as Driver
Assasin -- Silenced Gun, Sniper, Knife -- Hidden off The Map, Cloacking Ability when not shooting (30 seconds cloacking, 2 minutes and 30 seconds recharging)
Rocketeer -- Pistol, Grenades, Rocketlauncher -- Only type that can wield a Rocketlauncher, can bring down tanks and aeroplanes in a couple of blasts (homing missles possible)
Driver -- Pistol, Uzi -- Ability to Vehicle Spawning at HomeBase (Limit on each Type of Cars out there, f.e. 2 Tanks MAX)
Medic -- Pistol, Uzi -- Ability to spawn an medpack and armor every minute.
Supplier -- Pistol, Uzi -- Ability to spawn a bulletcrate every minute.
All-Round -- Custom Weaponchoice (No Rocketlauncher) -- No Special's, Only Custom Weaponchoice.
No-Violence Games
Skydiving - You will need a driver to spawn parachutes (if you plan to use them) and fly the plane. The Driver can jump too (plane will crash)
Biljart (Pool) - Erm .. read it somewhere? Not really needed, but small games like this are fun
Poker - Erm .. read it somewhere? Not really needed, but small games like this are fun
Basketball - Score Points and Win
Any type of mini-games are usually fun, which can be found in SA. If all of them could be implanted, that would be alot of fun!
Earning Money
BankRobber - Take out the guards, and rob the bank w/ your teammates. Each gets an equal cut of the profit!
Streetracing - The Admin could turn a streetrace on, you can participate in it and try to win the price money
Area 61 - Break into Area 61 and steal that jetpack! Then get back to your homebase and collect the money and devide it under your gang participants.
More to make up ..
You can buy weapons (if avaidible for your class) and play gamble games etc with it.
Admins - 3 Different levels of Admin should be access-able
Level 1 - Administrator
Activate Moneygames (BankRobbing etc..)
Activate Racing (Streetrace, Countryracer etc..)
Activate Gametypes (Read Build-In-GameTypes)
Hide a moneystash (CashBonus for lucky finder, admins cannot take it themselfs, its lame to tell your friends where it is after placing it btw)
Kick Player
Ban Player
Join PoliceForce
Punish Player (Force him into Spectate to 'think' about his actions )
Level 2 - Moderator
Activate Moneygames (BankRobbing etc..)
Activate Racing (Streetrace, Countryracer etc..)
Activate Gametypes (Read Build-In-GameTypes)
Kick Player
Ban Player
Join PoliceForce
Punish Player (Force him into Spectate to 'think' about his actions )
Level 3 - Overseer
Activate Moneygames (BankRobbing etc..)
Kick Player
Join PoliceForce
Punish Player (Force him into Spectate to 'think' about his actions )
Read Build-In-GameTypes (A player CAN join but does NOT have too)
Deathmatch (Select an Area f.e. LS)
StuntMode (Spawning the planes/vehicles and do the 'ordinary' stunt thingy
Survival (Select a player to be hunted (Teleported to Desert, and all the other players will hunt on this person, only players that accepted the challenge can hurt the 'Runner'. All participants will be teleported to their hometowns.)
Capture the Flag (Duuhhh, 2 'new' teams with each its own flag to defend and obtain)
JailBreak
SkyDive Challenge (Get Airborne and get dropped (Computer Control for good drop positions) and try to land as close to the marker as possible)
Assasin Mode - All gangs get the same opportunity by an Unkown ordergiver, to assasinate an NPC target. Whoever gets the killing shot in must return to their gangbase and collect the money of the assasination. Assasins can attack assasins, if an assasin dies he is out of this Assasin Match. Assasins can only do the actually NPC Killing, so help of others is very handy (Gunman to rifle down other assasins f.e. and medic to heal that assasin). Everyone can play as an Assasin, their is no gang Assasin limit. ( Based upon suggestion )
Feel Free to improve anything on my 'design', i hope the team and the visitors like the idea and perhaps even use it oO, we'll see.
(btw i do not expect something as huge as this on a initial release, but it would be great to have this as a final product)
Please don't reply if you dont know what your talking about.
If you would like to see this gameplay alive please reply here and say what u can do to help us
not a fan of any GTA game, but still, the multiplayer aspect intrigues me 
