One army is Yellow. The other is Red. The other is Blue. The goal is to be the last army standing. No peace treaties or alliances, just a fight.

Each location has advantages and disadvantages. Three people must play, I will oversee the game.
Each army has: 50 Soldiers, 30 Scouts, 20 Archers, 10 Cavaliers, 10 Heavy Knights, 5 Mages, and 1 Hero.
Soldiers: Wear medium armor, know how to cross the terrain at a fair pace. Carry a spear, small circular shield, back up dagger.
Scouts: Leather and light armor, carry shortswords. Know how to travel the terrain very well at a fast distance, and can make booby traps. Good at dodging attacks.
Archers: Unfamiliar with terrain, slow moving. Carry longbows capable of reaching good distance, good aim. Also carry shortswords which they are not well trained with.
Cavaliers: Horse mounted lancers. Have a hard time moving through the forest and the mountains, but can other wise move quickly. Carry long lances and longswords.
Heavy Knights: Heavy armor makes them difficult to harm, but very slow movement is hampered even more by the terrain. Carry either lances, or large axes.
Mages: Capable of offensive magic only, and only simple spells at that. Familiar with terrain can move at a fair pace, but extremely easy to hurt and kill.
Hero: Your choice of weapon, back round and ability. Keep it fair.
RULES:
You oversee this army as a general. You can watch your troop movement, as if from a birds eye view and give them commands on the fly. (Think RTS game.) As enemy fortresses are some distance away, you will probably be walking. Your troops need supplies, they need to eat and rest. Archers run out of arrows, and things can break and go wrong. I will be managing fights, they will be determined randomly, with some factors (such as which class is attacking which and other such advantages) determining the out come. I will also randomly have events occur, such as a broken sword, an illness, broken bone, etc. which will also be distributed randomly.
Otherwise, have fun and us your head in this. Be sure to study the map.