Has anyone figured out when a game is setup for a 303 result? Or is every game possible to end that way? I've played a few games where I used every HP as efficiently as I could, but came up 1 HP short at the end and ended at 302.
On the other hand, today I had a game where I accidentally used a heart life refill instead of leveling up, which I thought would leave me short at the end (since the heart refills are more powerful if you are a higher level), but that one I ended exactly on 303.
Not sure if it's randomness with the brick walls maybe? Or there might be a strategy to those that I haven't grokked yet.
Heart scrolls restore your entire HP bar, which means that the higher level you are when you use them, the more powerful they get. So if you want the most bang for your buck you need to level up quickly without losing health.
-Find and kill the Lich the moment you get to 11 health. Since the Lich lets you take mines for 2 XP, he actually gives you more XP than the HP needed to kill him
-Find chests quickly, some chests give free XP
-About this last bit I'm not entirely certain, but I usually don't attack wall until I'm sure I can destroy all of them in a single health bar. This is because while walls as a whole give more XP than they take to destroy, you never know how strong any single wall is, nor how much XP it will give you
It's always possible to completely clear the map, and in fact, there's quite a lot of leeway here - it's possible to have cleared every square apart from the dragon, and still have a healing scroll, plus up to about 10 spare gold.
It's almost always possible to get 303, but very occassionally, you will clear the map and still only get 302, which I believe is due to a glitch in the level generation system.
If you run out of moves late in the game, it's because you played "inefficiently" earlier on. Using a healing scroll while you still have hearts remaining, is the most obvious source of inefficiency, but not the only one.
As you have already realized, the higher your level, the more hearts you gain from using a healing scroll, so using hearts while you're still at a low level is inefficient. In general, you will spend 1 heart to gain 1 gold, but there are ways to improve on that ratio, or even gain free gold:
1.) Walls - there are seven walls, and the ratio of gold received : hearts used to destroy, varies as follows: 1:1, 1:2, 1:3, 3:4, 3:1, 3:2, 3:3 (so the average is actually very slightly worse than the 1:1 ratio of normal monsters). Ideally, you would destroy the two walls with a ratio better than 1:1 as early as possible, and leave the others until later.
2.) Chests - two of the chests contain 5 gold each, and they don't cost health to open, so the sooner you find them, the better.
3.) Mines - there are 9 mines, worth 2 gold each, and they don't cost hearts to destroy, so the sooner you destroy and reveal them, the better. Make sure you already know where the you-know-what is, by the time you have enough hearts to kill them.
4.) Gnome - gives you 10 gold, but only after all empty spaces have been revealed, so ideally you would mark as many spaces containing monsters as possible, without killing the monsters until after you've caught the gnome (also don't destroy walls until after you've caught the gnome).
In general, the main key to winning is to expand the revealed area as quickly as possible, as cheaply as possible - it's usually better to kill low-level monsters than high-level monsters (cheap), and better to reveal a space you know contains a low-level monster (even if you're not sure exactly what it is) rather than killing a low-level monster that was already revealed (quick).
Not sure about the walls - I think a proper statistical analysis would be quite complicated.
On average, the Gold:Heart ratio of walls is almost identical to that of normal monsters, so I don't think there's too much wrong with just treating them as such, and destroying them anytime it helps you open up an area of the map that you want to explore. You just have to avoid situations where you're on 3 hearts and relying on a wall to give you the last 3 gold you need so that you can level up.
You could track which specific walls you've already destroyed, and figure out the probabilities for what's left, but that's too much work for me, and not necessary.
I suppose the ideal time to use them would be when you have 1-2 hearts left, and need 3 gold to level up. Spending those hearts on killing monsters doesn't really help you, but there's a chance that a wall will break in 1-2 hits and give you the 3 gold you need, to save you wasting a healing scroll.
I tend to mostly use them when I'm about to heal or level up (and already have enough gold), but have an awkward number of hearts left, that I don't want to waste - particulaly very early in the game (when there might not be many rats about), and very late in the game, as you're mopping up the final few monsters, and burning through those healing scrolls.
Additionally:
Rats: Will always face the column that the Rat King is located in. Any rats within this column will sit upright and not face any direction
Gargoyles: Will always appear in pairs facing one another. Their eyes are indicators of where their partner gargoyle is located (i.e if one has two eyes, the partner is below. If it has one in a direction, it's left or right, and if it has no visible eyes, its above.)
Gazer: Will obscure a diamond of spaces 2 above and 2 aside itself. Only two will spawn.
Big Slime's & Warlock: The Warlock will always appear against the edge. The 5 open spaces surrounding him will be filled with bug slime's (since he cannot have 8, as he will be present in an edge. I do not believe he can appear in a corner).
Lich: Always appears in one of the corners of the map.
Additionally:
-Five chests (And one Mimic) will always spawn. One of the will always contain a scrying orb. That leaves you with two chests that contain health, and 7 revealed health scrolls.
-Though there seems to be no limit as to where the gnome can spawn, because of how the game generates, he tends to remain closer to the edge of the map.