Here's a list of game modes in COD and how much teamwork they require:
-Free for all: Everyone for themselves. No teamwork.
-Team deathmatch: Well its team deathmatch. Still teamwork isn't vital as someone good can singlehandedly change the game.
-Kill Comfirmed: TDM but you have to collect tags. Same as above for teamwork.
-Domination: King of the hill variant but with 3 permanent flags in the map. Teamwork REALLY helps, but can be played alone.
-Ground War: KC/TDM/DOM but with bigger 9 V 9 teams. Teamwork becomes more important here.
-Demolition: 2 bomb sites which have to destroyed with one team on offense, one on defense. Teamwork is quite important to plan an advance on the bombs or to defend them.
-Headquarters: Have to capture designated areas in map for a short period of time until it moves. Again teamwork is quite important but can be attempted alone.
-Capture the flag: Its CTF. Teamwork helps very much, but can go solo.
-Sabotage: Neutral bomb in map which needs to be picked up by either team to destroy the other's bomb site. Teamwork is paramount.
-Team defender: Similar to CTF but people grab and hold the flag to score point for the team. Again teamwork is extremely important to lock down flag effectively.
-Infected: Similar to infected in halo, one guy starts off infected and knifes to infect others. No teamwork necessary.
-Drop zone: Moving capture zones which when captured give free killstreaks to the team. Can be played by yourself pretty easily.
-Hardcore game modes: Low heatlh+no hud version of dom/tm/ctf, etc. Similar to what is stated above.
-Barebones game modes: No killstreak game modes of tdm/kc/dom. Similar to what is stated above.
Most played game mode is TDM followed by KC I believe.
Well I think you get the picture that there are modes to accommodate both team and single players. If you are playing as part of a team, you will rickroll randoms. But if you are a very good player, you can contest an entire opposing team by yourself. I personally play by myself quite a lot and don't bother even picking up my headset because all I hear is racist and whiny people complaining about how they got owned. So unless you have a clan or a party, don't even bother trying to talk to your team as they will only start insulting your mother. Just put on some metal in the background and pwn some noobs.
