Very nice game! Finally managed to solo through it using a Barbarian. That charge is seriously awesome.
I agree with what others have said here; the Summoner seems very weak, even when taking into account the fact that INT increases their damage output (probably because they don't have any actual special ability for any form. They can't really shield like a knight can, for example)
How complicated is it to make a dungeon map w/ events? If it's something like a level editor maybe you could release it to the good Tig People here and I guarantee we'll come up with 50 more maps you might be able to incorporate into your game (after you add the random events of course).
I look at the levels of the game; it doesn't seem like it would be all that hard to make a level yourself if given a level editor. The levels are just maps with enemies and events placed which have effects when you run into them. As a user of various game making engines, I could easily picture a user-friendly creator that could work to make custom levels.
Anyways, I'm silly and like to formulate new things, so I'll edit this post with like a few custom classes.

EDIT:

From left to right:
Lancer
An alternative to the Knight and Barbarian, the Lancer is a strong, heavy upfront fighter with a slight bonus to strength and a large bonus to fortitude. He wields spears, which have a massive forward range, but also have a long attack time (and thus rapid jabs cannot be done). Their special is a charged spin attack that easily clears out enemies all around themselves. He doesn't quite have the shear lasting power of a knight, nor the surprising forward strength of a barbarian, but he most certainly makes up with his excellent crowd-control capabilities.
Fencer
Another fighter alternative, the Fencer is the most agile 'fighter' subtype, somewhat similar to the bandit. The fencer requires accuracy and strength to use, and augments these stats. The fencer's special is the counter-attack, which allows the fencer to absorb one incoming attack and return its force in full back at the attacker, deflecting projectiles, and returning melee attacks with a fierce, powerful lunge. The fencers blade swings quickly, and fast movement allows him to easily step out of the way of attacks. He's quick and hard-hitting, but a wrong move can spell doom, since the fencer is not necessarily adjusted well for taking hits.
Illusionist
The Illusionist has a three-fold approach to his style, requiring mainly intellect and strength to properly be used, but also certainly has attributes of stealth to his style. Illusionists use the staff, but are most certainly not afraid to use it to hit. True to his namesake, the Illusionist's special is a charged effect, which has rather powerful effects for each level charged:
Level 0(quick tap): Mirror laser; fires a laser which bounces off a wall at a 45 degree angle, then continues to bounce off other walls at 90 degree angles. Does roughly about 1/4th the damage of a staff swipe, and only 3 lasers can be fired out at once.
Level 1: A single illusion decoy is laid down. Enemies will attack it until it wears off.
Level 2: Illusionary mirror images surround the Illusionist, making him a tempting, but hard-to-hit target.
Level 3: Group hide; instantly hides the entire party. Every member is, thus, capable of backstabbing with this spell.
A powerful and versatile class. Its versatility is obviously limited to how much time is available to him to charge, but that's what his illusions are precisely for; to buy time.