Basics
This is the map:

The flag begins in the center. Tails are pretty short, but it still gets crowded, because the arena is very small. Physics will be familiar to any sumo/fort players, but rubber is lower. Auto-respawn is on and set to 8 seconds. There is a DZ after 2 minutes.
Scoring
11 points for holding the flag (for 10 seconds)
2 points for a kill
2 points for using a teammates hole (cancel out a kill with a hole usage)
300 match score limit, and your team must win by 30 or more points.
Flag stuff
You can only score once per flag hold. You will drop the flag automatically after 16 seconds, or 6 seconds after you score. If you auto-drop, the flag goes to the center of the map, where it may be a free-for-all as to which team steals it next.
Rather than auto-drop to center, some players have begun manually dropping the flag so that a teammate can pick it up. This is done with the /drop chat command, which can be set as an instant chat. With /drop, you can sort of pass or hand off the flag to a teammate.
If you drop the flag, you specifically cannot pick it up again for 10 seconds, or until someone else has touched it. Some players find it tactically useful to drop and defend, perhaps if their teammates are dead (unable to receive a pass) and an enemy is controlling the center.
With this relatively simple dynamic, Fox Hunt is fast paced, constantly dynamic game mode. Because of the flag the changes hands every 10-16 seconds, the game never stalls out or gets into a lull. Respawns mean you are almost always playing, and almost never watching, unlike sumo or fort. The best teams so far have been good at passing the flag, which requires a decent amount of teamwork and skill in a crowded grid. Best with 3v3, but perhaps easier with 2v2, as there is more space and it is easier to coordinate with fewer players on the grid. It is a lot of fun.