Maybe you can't take part in the Legend of Grimrock 2 closed beta, but you can still help out with the testing process. Almost Human Games has released a non-interactive compatibility testing tool that will tell you whether the game will run on your PC, and help the studio figure out what the trouble is if it won't.
To be clear about it, this isn't a demo, or playable in any way at all. It simply draws a (probably familiar) image on your screen, animates it, and plays the bombastic Legend of Grimrock 2 main menu music until you press escape. You can, if you are so inclined, use FRAPS (or your benchmarking software of choice) to see how it performs on your system, but otherwise there's not a much else to see or do.
Things get slightly more interesting if it doesn't run. The software writes a log file recording the basics of your hardware and the tool's video settings, and if things don't work out as they should, that file can be emailed to Almost Human so they can dig into it further.
There's also a config file that can be manually adjusted, for those who want to futz around with various video settings to see how they impact performance; it's obviously not the most user-friendly way of doing things, but odds are that if you're interested in it to that extent, you're comfortable enough with that sort of under-the-hood shenanigans anyway.
The compatibility tool is available at grimrock.net. Legend of Grimrock 2 comes out on the alarmingly-close October 15.