Discussed a bit on discord. The idea is that the player would select a flagstand to defend, and then try to stop pre-recorded attacks from taking the flag back to a particular safe zone (a flagstand, a designated area the attacker's team is assumed to occupy, or perhaps just the other half of the map).
The recorded attacks would come from player submissions. Attackers may select any spawn tube to begin from and the flagstand they are attacking, then record their route. A leaderboard will track the success rate of the player-submitted attack routes.
Particularly successful routes can inspire new races, etc.