What I liked in ET and ETQW is that there is an evil team (nazi, strogg).
This element alone create a difference between the 2 teams.
totally agree with this, although i am not especialy for an “evil” team but more for a real difference between the teams that is somethin that bother me in most fps : no differences between teams results in no incentive to fight
even in tf2 wich have great characters, the fact that they are twins on both side feels stupid and dont justify any fight
war and battle in human history has almost always been justified by “the others” “the different”
i think we need to know for what reason we fight ( appart for “money” as basic mercenaries )
for that matter i think brink approach was great for difference between teams and plot
maybe starting by writing a story ( or if it is already the case, just make it more obvious) that explain the situation and clearly identify 2 positions
like for instance the government who has destroyed london on purpose and want to hide evidence and maybe even some experimental area
and on the other hand freedom activists who search for these evidences and / or want to destroy these experimental research area