But to answer your question (coming from a college student): My first thought was to be able to pre-order these games, but you said that didn't work.
What about instead of selling the games, since your main idea is focused around the system requirements- you could do affiliate linking to the products users need.
Then they see exactly what they need, and appreciate + gladly go through your link to get their system to the playable level?
I'll be able to go to gamers-lab.com, find the game I am interested in, "Run this game", and if my computer dosen't meet the specs required I'll find the links easily I need to upgrade my rig. Sounds like a pretty slick service to me.