Various things RUIN this game. How do you shut off one or more:

1. Being wildly outnumbered in every single scenario?
2. The extremely-aggravating time limit (gold, silver, bronze)
3. The enemy having a huge number of elite units?
4. The totally inadequate amount of available gold?

I do not know about mods but there are a few simple cheats that you can use to level the playing field. They can add gold, xp, or just victory. How much of a challenge you want is up to you. Google can provide all of these cheats but for the benefit of those who are interested:
Hit the "~" key (top left on keyboard) to bring up the chat box.
Enter "cheat_______" followed by the code.
For example, to add 100 gold you type "cheat100gold" and hit Enter.
Here are the codes:

10exp - Ten experience points
10gold - Ten gold pieces
100exp - One hundred experience points
100gold - One hundred gold pieces
1000exp - One thousand experience points
1000gold - One thousand gold pieces
defeat - Automatically lose mission
heal - Automatically heal
resurrect - Revive slain units
shadows - Create shadow for units
victory - Automatically win mission