Amagami is currently PS2
and PSP only. Some fans have tried to translate PSP games, with just a little success so far. Idolmaster SP is a work in progress, but the people striving to translate some licensed PSP games — Oreimo, Haruhi, Toradora — haven't made much progress.
If I could have just one translation get done and released... I'd probably say Sakura Wars
3. It's been said to be the high point of the series, It was first on Dreamcast, and later it was ported to PC. It has both gameplay and narrative. Nothing obscene, and a mix of drama and comedy. There's an OAV or two based on it, but the only way to appreciate it in English is a walkthrough or two on GameFAQs
One troper asked, "...how does one find something interesting if you can't understand it in the first place?"
Adaptations, art, fan works, and fan-generated hype. There's many untranslated games which have professionally translated anime and manga spinoffs. Some fans get into untranslated games just because they like the CG images. Other fans pay attention to untranslated games because someone creates an amusing fangame like NANACA†CRASH!!
, or a humorous meme like Carameldansen (from Popotan). And then there's a small number of fans who actually read Japanese, and start talking in positive terms about what they enjoy.