rpg - Balancing Player vs. Monsters: Level-Up Curves

I've written a fair number of games that have RPG-like "levelling up," where the player gains experience for killing monsters/enemies, and eventually, reaches a new level, where their stats increase.

How do you find a balance between player growth, monster strength, and difficulty? The extreme ends of this spectrum are:

• Player levels up really fast and blows away monsters without much effort


• Monsters are incredibly strong and even at low levels, are very difficult to beat

I've also tried a strange situation of making enemies relative to players, i.e. an enemy will always be at 50% or 100% or 150% of player stats (thus requiring the player to use other techniques instead of brute strength to succeeed).

But where's the balance, and how do you find it?

Edit: For example, I am expecting to hear things like:

• Balance high instead of balance low (200 HP and 20 str is easier to balance than 20 HP and 2 str)


• Look at easiest vs. hardest monsters, and see what you have in terms of a range

Answer

Playtest. No, really, just playtest your balance until you get it right, or rather mostly right (there's no such thing as perfect balance).

Write automated tests and run them hundreds of times. Even very simple automated tests, like "level 2 player always hits with shortsword, goblin always hits with club, player should win" can really help, if you run these tests often (generally, whenever you change anything). Also, test balance by playing. Whenever you find some new potentially balance-changing tactic, write an automated test for it.