So, stumbled across some interesting sounding games – portable, short play time, relatively inexpensive.
Space Marines Adventures: Labrynth of the Necrons
was easy to find – $25 USD at Amazon
Seems a relatively simple, quick game I could play with my kid. Go kill monsters for 30 minutes. Make popcorn. Kill monsters for another 30 minutes. Etc.
Then a quick check at Boardgame Geek shows that there are several other games:
Space Marines Adventures: Rise of the Orcs
Space Marines Adventures: Doomsday Countdown
Space Marines Adventures: Rescue Pack Expansion
Space Marines Adventures: Recon Pack Expansion
Space Marines Adventures: Promo cards
These I can find out nearly nothing about – not at GW's website, nor almost anywhere else.
Then, a bit more involved, was "Fireteam" which sounds more interesting for an adult, but is not available anywhere, except… Wait for it… Barnes and Noble?? And there are supposed to be some more miniature packs for it, and those are nowhere to be found.
So, is GW just trying to not sell things?
I'm open for some explanation from those who know better, and may have leads on where GW sells their intro box games now.