Map 800 is the Christmas event map for 2011 and 2017. In this map every mouse is a shaman. You cannot receive any event items or titles from this map, unlike most of the event maps added. After playing the map points on the leaderboard are not reset, unlike other maps with shamans.
Simply go to the cheese and go back to the hole. However, in this map all the shamans try to kill each other, so it is also a bit like Survivor. However, unlike Survivor, you are not the only shaman and your cannons are not at the top of your item box, so be ready to start summoning before someone else cannons you to your death! And in this map you can use portals, so you could use those to stay alive or attack. Just note that all shamans use one set of portals, so the two portals will not stay where you want them to be since other shams can move them, as well as you.
Only the last shaman standing will be able to enter the hole. Since everyone is a shaman, they will earn experience points for "saving" the shaman that entered the hole.