I think the lack of exploration/choice of map expansion in the campaign could be partly solved by allowing the player to chose to unlock a new area like city skylines based off total research points. Maybe with a bonus for certain key researches.

With the competitive aspect, what if there to make a RTS style game with team based biters ?

A lot of people have mentioned bots and AI controlled cars and tanks but I haven't seen much mentioned about using biters to fight another side.

Here's a few ideas and points to consider

Research Tiers ...