Loadmapstate

loadmapstate restores the current map to the state it was in when the savemapstate command was last used in that map.

Thus, all the sprites will be in the positions they were in at that time, any sectors that were activated will still be activated. Per-player and per-actor variables will be restored to the values they had at that time unless they were declared with GAMEVAR_FLAG_NORESET, etc.

If there is no cached copy of the map (either because savemapstate was not used in the map or the state was cleared using clearmapstate) then loadmapstate does nothing.

It is sensible to run loadmapstate from EVENT_ENTERLEVEL because running it after a startlevel command won't work as expected.