This seems to be the opinions only of people who havent learned our game yet. Thats not to say the opinions arent meaningful, just that all of us who know better, know because we took the time to learn and understand the game's teamplay system.
Ive had the experience to learn, you should allow yourselves the time to learn also. In tf2 the classes are mirrored so of course you need to set them apart with graphics and they chose outlines... well in GE:S its character based not class based, and on each team there is assignage as said "bad guys vs good guys" once you learn what that means.
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Think of it this way, in a james bond movie you can assert from plot if a character is bond ally or villian. In the game we create it relates only to goldeneye and the original game sure, but is already well layed out for you with our selection menu what team a player is. Its clearly written and all you then need to be aware of is what team you chose, and to shoot people on the opposite team.