I would love CTF & KOTH modes.
Q3 (ie FT), UT, SM (jailbreak idd!) & some HL mods have really fun game modes. It’s often far less played than the main ones but it can be a welcome break and it can really thrive from a open modding community.
I also have in mind TF2 Payload Race game type. Current EV mechanic is terrible, but if it gets improved (with for instance a faster default speed and also a speed based on surrounding players), it could be a fun mode imho. In TF2 both teams have a wagon cart to escort (starting points a few meters away from each other or at an opposed direction symetrycal map), of course the goal is to reach the finish line first but you can do it so by gluing around your cart to increase its speed and/or by killing the enemy cart escorters, stopping them from making any progress.
The twist in DB is that you could destroy the enemy EV, forcing its team to repair it and losing ground doing so.
If maps are well designed it could be fun (EV start points at opposite sides of an avenue / course progressions on different streets separated by open buildings / courses crossing each others at hotspots / etc).
