I made it to Level 8 and Day 8.
Ultimately, what it seemed to boil down to was running around in a wide circle to kite most of the enemies, and then the enemies which spawned were the only tough ones to avoid. It might have been my luck, but they suddenly started spawning at least five times faster when I got to day 7.
It'd be nice if the flame can employ a temporary mode (or burn something) to grant it immunity or the ability to kill spiders. It'd also be nice if the trees had a slight growing animation. Popping up trees is somewhat silly, I think. :p Could also have a burning trail. Grass isn't immune to fire!
I'd also love to know how many trees and shrubs I burned in my wake. :o
Finally, another thing that'd be nice is to make it into something like 3 factions, where you must avoid say, rangers as well. The spiders and the rangers are also trying to kill each other. All in all, simple enough to play!