It would be nice to let new players learn everything by experiencing it, for example this must contain 10 level and player should finish quest to pass level, for example quests can be 1-build a turret, upgrade it 2- use portal gun to go to that place 3-vote player id 6 and so on...
Its just a suggestion, if u think it would help player let me know to write it. And also it must be somewhere in games main menu in order to players see it.
I bet it exists in Call of Duty series. CS:GO also has this feature but hidden. Well, we can make a scripted map and then ask DC to upload the map to official CS2D's files and make wrapper in main menu ( DC or SQ part) to autoload the map for the first time.