Here's some thoughts (I've bought from @dgamesshop bvefore, but not you):

I think you have a good number of games. Overall, you don't want to have too much, but you also want enough to entice people who might be doing an impulse buy.

The Humble Monthly thing is something I'd have to do more research on. It seems like it's a good thing for people who have access to plentiful crypto but no fiat, but I'm not sure how appealing it is for people otherwise.

Discounted games purchase is definitely a winner, at least if you're not taking a huge loss on it. You might also do well to use a seller like Green Man Gaming that often offers promotions, or another service, and just send keys, though you want to avoid anywhere that might give shoddy keys.

Four featured games works okay, but some of this may depend on format.

One thing that I'd consider is some sort of genre divider for the overall games list. You've got some good stuff in there, but sorting through to the stuff that would be appealing to certain players could be difficult.