(0:71) When a furre stays in the same square for 2 seconds,
   (1:17) and they (moved from/are standing at) floor type #,  (River, first tile)
(0:71) When a furre stays in the same square for 2 seconds,
   (1:17) and they (moved from/are standing at) floor type #,  (River, second tile)
(0:71) When a furre stays in the same square for 2 seconds,
   (1:17) and they (moved from/are standing at) floor type #,  (River, third tile)
            (5:15) move the triggering furre to (#,#), or to someplace nearby if it's occupied.