Making a Skirmish Game for Kids

as the title mentions I am trying to make a skirmish game for kids

I bought into the Impact miniatures Adventure range. [here is the KS link so you get what I mean by Chibi http://www.kickstarter.com/projects/674003445/classic-dungeon-adventurers-miniature-set-chibi-an my daughter loves these minis]

so what I need is something that is K.I.S.S [Keep It Simple Stupid] and that will be fun to play and have chance to add to it and make it more complicated as the kids get older. 

After much thought I am moving away from the Dungeon crawl and heading in the Skirmish arena. 

Another way to look at this would be Warmahordes for kids. Something along the line of that rather then playing WHFB. 

so What I am wondering if there is anyone out there who has done some thing like this or even about where to start...

I have 7 factions so far:

The Kraven: <--- W.I.P not sure if its right
Ram Beastman (1) [Leader, Magic]
Minotaur (1) [Big guy]
Addix Beastmen (2) [Solos] 
Bull Beastmen (4) [grunts/meat shields] 

Dragonkin: <--- W.I.P not quite right.
Dragon Lord (1) [Leader]
Great Dragon (1) [Big Guy, Flying, flame breath]
Drakons (3) [Elites, Flying]  

Phire:
Phire Lord (1) [Leader, Magic]
Wyvern (1) [Big Guy, Flying, Flame breath]
Phire Mages (2) [Solos, Magic]
Phire Hounds (2) [Elites]

Nathair:
Lady Serpenten -Medussa (1) [Leader, Ranged, Magic]
Cobra Guardian (1) [Big Guy, Venom, Crush]
Serpon Leader (1) [Solo, Magic]
Serpon Cultist (4) [Tentacles, Grunts] 

Ponians: <--- Daughter hasn't decided if this is the correct spelling. [she wants Ponyins???]
Twilight Sparkle [Leader, Magic]
Rarity [Magic]
Apple Jack 
Pinkie Pie 
Fluttershy [Flying]
Rainbow Dash [Flying]

Knights of Valour: <---- Son's Faction he is not sure what to call them
Sir Dominik the Brave Knight (1) [Leader]
Sir Eric the Ernest (1) [Solo]
Scarlett the Warrior Princess (1) [Solo]
Iron Maidens (3) [Elites, Halberd]  

Deamham:
Droch (1) [Leader, Magic, Flying, Terror]
Jack O'lantern(1) [Solo, Magic]
One Eyed Demons (2) [Elite]

the history and back grounds will come together over the next few weeks. As I sit down and work it out. 

I am wanting to have equipment cards, event type cards that effect the game, ability to search enemy bodies, characters/solos/grunts gain experience as they play campaigns, missions and scenarios that can deal with Solo, two and group play. 

The two ways I could do this is either as a Skirmish game [as I mentioned earlier Warmahorde Jr] or play it on a grid format and make it like an arena style game. [sort of Gladiator or Pit fighter style.] 

I want to also create a Stat calculator that takes into account race, abilities, skills, experience, etc... [not some thing I know how to make or where to start but I'll give it ago.]

So anyone got any ideas? I am wanting each of the units, characters and big guys to have a stat card, that has all of their abilities, costs, spells, stats, armour, etc.

but it has to be usable by a 5 and 7 year old. but the game can and will grow as they do so it has to be able to become more complicated.

cheers
LGW