Hey Joe, Thanks for sharing your idea. I would really love to hear more about your solo tasks and see some pics please.
Back when Cube Quest was called KingBrick I listed some alternative / mini-games on the (professionally designed, state-of-the-art) KingBrick Website.
You or your nephew may be interested.
A couple were basically the normal game but with a twist.
* ANNIHILATION: Object is to defeat ALL enemy cubes not just the king. Turns normal strategy on it's head! King becomes best attacker!
* '100': Winner of each 'battle' is awarded points for the cubes they still have in play. First player to reach total of 100 is victorious.
Cubes only games (No board required) -
* ROLL'EM: Players roll a set of cubes, simultaneously. Whoever rolls the most cubes 'happy' side up defeats a 'sad' side up cube of their opponent's.
* STACK'EM: The tricky task of stacking up lots of cubes!
* TOWER CHALLENGE: Simple game involving cube stacking. Player's don't want the tower to fall on their turn.
* DUEL: Needs a bit of floor or outside space. Player's try to knock each others king off of a cube structure, at distance.
Flicking practice game -
* SIEGE: One player has four flicks to knock cubes out of their opponent's castle. Final positions of all cubes give a score.
For details please check out http://kingbrickgame.com/page6.html
. Yes, it's still there! (Please note that cubes were called 'bricks' in KingBrick. They had happy/sad faces instead of the character/shadow sides of Cube Quest. KingBrick Guards and Champions became Cube Quest's Grunts and Strikers respectively. Also the points/cube-costs were tweaked. A 5 point Champion brick is now a Striker with cube-cost of 4.)
Mainly aimed at children, I found these little games offered variety and versatility. A game that only required a few cubes can be played almost anywhere. Roll'Em on a train journey, Stack'Em on your desk, Duel in the playground! To be honest I hadn't really given solo-play much thought until now. I suppose both Stack'Em and Siege could be played alone as they are more like practice exercises. I am very keen to hear more ideas please.