Bite-Sized Update:
Replace some enemies with powerful Randbosses. Enemies of a Unique rank or higher, who are given random class talents.
Every rank of enemies has their own tier of loot.
As you level up, you'll see more of these buggers walking around.

You spawn at level 12, and can level up to a maximum of 200.

Increase your rank as you slay your foes.

You can see your kill counts and your rank experience in the quest log.

Prodigies have minimal requirements and you can get one at level 1.

Contains a new melee class - the Blood Knight

Details & discussion here:
http://forums.te4.org/viewtopic.php?f=50&t=40159

Version 3.0: Compatible with ToME 1.5.0

This addon supports game play for character levels higher than 50, primarily for the infinite dungeon (I.D.). This implements a number of subtle changes, rescaling game mechanics and balance for character levels above 50 in the Maj'Eyal, Infinite, and Arena campaigns for ToME. The intent is to make it possible (though certainly not easy) to reach level 500 of the Infinite Dungeon. This is not a nerf or a buff to game difficulty per se, but, rather, an extension of the well-balanced game play from the Maj'Eyal campaign to higher levels.

Some talents and status effects have been adjusted to accommodate the higher character levels possible. You can see a summary of these by checking the "Infinite500" tab in Game Options.

Once a character enters the I.D., the level 50 cap is removed and normal stats-per-level progression is enabled from level 51 onward. The limit on how high primary stats may be trained is removed (limited by character level as normal) and dependent computed value limits are also appropriately increased. No additional Prodigies are gained automatically after level 50. (Note that additional category points and (rarely) Prodigies can be gained by completing I.D. challenges.) Talent mastery levels can be improved more than once, and talent levels are unlearnable as normal in the I.D.

NPC levels in the I.D. have been adjusted to be compatible with higher game difficulty settings.

Most monsters and bosses from the Maj'Eyal campaign are imported into the I.D. along with their respective unique drops.

Traps have been added back to the I.D.

Isolated shops can appear randomly in the I.D. There is guaranteed to be at least one shop on level 1, and they become more common for the first few levels, and then more rare with depth.

Random escorts may be randomly generated on each level in the I.D. unless a challenge has been started, until the normal number (9) have been attempted.

The lichform quest is completed in the I.D. with a new random drop instead of automatically being completed at the appropriate step. There is a new greater vault in the I.D. that affects this quest.

The Corruption/Hexes tree can be learned from a new random drop.

Most major events from the Maj'Eyal campaign are enabled in the I.D., and there is a new event that can award the cursed-aura tree.

Undead characters starting in the I.D. begin with an artefact cloak. This is similar to the Cloak of Deception, but its stats scale with character level and it can spawn randomly for other characters.

This addon incorporates some modified game mechanics:
The ability to shrug off critical hits has been changed. Instead of using the percent value to ignore crits completely, it reduces the crit multiplier by the same amount to a minimum of 100%.

Modified checkHit and checkHitOld functions are employed that allow for wider level differences between opponents (see http://forums.te4.org/viewtopic.php?f=36&t=35229).
Saving throws have been modified slightly to make them more effective at reducing the duration of status effects you fail to save against. (See http://forums.te4.org/viewtopic.php?f=36&t=36715 for details.)

Things planned for the future: scaling of world artefacts with character level, map effects with dungeon level.

CORE CODE CHANGES
Key code changes appear in:

Engine:
engine\generator\map\Static.lua
engine\interface\ActorStats.lua
engine\interface\ActorTalents.lua

TOME Module:
mod\load.lua
mod\resolvers.lua
mod\class\Actor.lua
mod\class\Game.lua
mod\class\GameState.lua
mod\class\Object.lua
mod\class\Player.lua
mod\class\interface\Combat.lua
mod\class\interface\TooltipsData.lua
mod\dialogs\LevelupDialog.lua
data\birth\worlds.lua
data\general\events\damp-cave.lua
data\general\events\drake-cave.lua
data\general\events\fearscape-portal.lua
data\general\events\naga-portal.lua
data\general\events\old-battle-field.lua
data\general\events\rat-lich.lua
data\general\objects\world-artifacts.lua
data\general\objects\world-artifacts-far-east.lua
data\damage_types.lua
data\quests\lichform.lua
data\rooms\greater_vault.lua
data\zones\infinite-dungeon\events.lua
data\zones\infinite-dungeon\npcs.lua
data\zones\infinite-dungeon\objects.lua
data\zones\infinite-dungeon\zone.lua
data\zones\ruined-dungeon\grids.lua

Other addons that affect these files might not be compatible.

This addon allows players to adjust the amount of exp they gain per kill via Game Options.

The current allowable range is 0% - 1000%, with 100% being the default rate. The range can be expanded if there's demand for it.

The adjustment rate will be set to the default of 100% for each new character made, and once set will remain persistent for that specific character.

Also, the level cap on gaining exp from lower leveled opponents has been removed for increased flexibility.

Please let me know if there are any issues.

Incompatibilities: There shouldn't be, unless you name your class "Hero" also.