Even though this is not for big armies like the usual game, you can try those kill-team rules (that fits for games between 200 and 300 points)
http://heralds-of-ruin.blogspot.co.uk/p/kill-team-rules.html
Each characters is played as an independant character (with some exceptions) and there is the notion of XP, level-up and custom gears for all your units.
Also, sweet choice of up-to-date codex/armies that
GW doesn't care to support these days. (Like Genestealer Cults)