In terms of the "bundle" theme, here are my ideas:
(1) "definitely a roguelike" -- obviously up to some interpretation but I think we all know it when we see it
(2) multi-platform -- no one feels left out
(3) new-player friendly -- no player left behind, Darren's guidelines are a good place to start, although I don't agree with 100% of them: clear interface, simplified key mappings, mouse (less Nethack, more Brogue)
(4) "lunch break" sized -- medium sized RL. Heftier than a 7DRL, but not super-dense. Not remaking Crawl or ADOM.
In terms of setting or genre, I don't think we need or want a restriction. (e.g. the 'space roguelike bundle!!' is not necessary, but would certainly be amusing)