Just tried
Hammer Wars. It's a ruleset created to play WHFB vs WH40K, but is a game that, albeit very simple (one page), has its own identity and deserves to be tried.

The most interesting aspect is that the "armies" aren't deployed before the game starts, but constitute a "pool" from which to summon, turn after turn, the models on the table. Destroyed models are made back in the pool and available again. This kinda reminds 'RTS' videogames. I found the game really enjoyable. Do not expect the system you'll to want to play for months or years, but for a casual game every now and then it is a really neat option.
Also, it's free!

I wrote morein depth here:
https://gabbigames.wordpress.com/2016/01/16/hammer-wars/Or you can download it and read it yourself. Probably it's shorter than my post

Download:
https://onepagerules.wordpress.com/portfolio/hammer-wars/