I love tagging to death. But the tag system on this board is pretty limited. But that's fine--it's not intended to be a comprehensive description of a game's content.
There's the game recommendations board--you could start a thread asking over there about games with large penises.
Frankly, a comprehensive booru-style porn game user-driven tagging and organization system would be kinda nice--think vndb.org but strictly for finding porn games rather than just VNs. You sorta have this kind of thing with sites like hitomi and e-hentai that host game rips. They tend to have pretty robust tagging, but they're far from comprehensive.
I mean, the reason that boorus are as popular as they are is the simple fact that people get so particular about what they see in their porn. If I want to find only furry women with breasts larger than their head getting a cumshot in the mouth, I can do (and, admittedly, may well have done) that. Or if I just want to see every image the site hosts with black-haired women and three men, I can do that. Takes a huge amount of user buy-in to keep a tagging system going when you have a load the size of gelbooru or e621's, though. But a single person or a small group could conceivably run an adult game indexing site.
Christ, if I was working I'd seriously consider throwing money at getting an idea like that off the ground. It could even be kinda fun. Spin up a kickstarter page on one of those adult kickstarters and all that; might even make it break even with ads.
