I'm working on a dungeon crawler board game (not an RPG). One player is a dwarf navigating a maze, and the other player spawns monsters from his or her hand to try and kill the dwarf. In the game, the dwarf can gain experience and loot by defeating enemies. As the game progresses, the dwarf can also add armor and other weapons to be better in battle.
I'm wanting to create a level up system for the creature player as well, but I'm stuck. Currently, the creature player has a spawn point limit and each creature costs a certain amount of spawn points. I would like to increase the spawn point limit as the game progresses, to make it more challenging for the dwarf player. My first idea was to have the amount of spawn points equal to the value of the dwarf's armor and attack value. However, I don't like this because the creature player's strength is passively determined by the other player. I'm trying to think of some system that allows the creature player actively strengthen his spawn limit; however, I want it to be loosely tied to the dwarf, to make sure that the dwarf doesn't get too much of an advantage.
You guys have had many great ideas! To clarify on what I'm looking for, I'm trying to make it where the bad guy player can increase the deadliness of his or her monsters through strategic decisions. I don't want the monsters to get harder automatically. So, gaining a certain amount of XP each turn is not exactly what I'm looking for.
I really like the deck building idea, the idea where more monsters generate more spawn points, and the idea where specializing in specific monsters makes it easier to spawn them. I'm not sure if I'll be able to combine these ideas, but I'll try. Would you guys give me some suggestions in this area?
Let me give you some more information about what I was initially thinking for the game. The game contains a shuffled monster deck. Each turn, the monster player can draw some cards from this deck. Each monster card has a spawn point cost, attack value, defense value, HP value, damage value, and a special ability when played. In addition to monster cards, there are also upgrade cards that can be used to strengthen monsters (e.g. armor, weapons, level ups). Each turn, the player can play a certain amount of cards with a total spawn point cost equal to the spawn point limit. The player may choose to spawn the monsters on the board (blocking passages until the dwarf battles them) or play the creature's special ability and discard the card. Monsters on the board do not move and only fight when the dwarf attacks them. To directly attack the dwarf, the monster player usually has to play the creature's special ability.