A retroclone is basically D&D/other RPG in all but name. Mostly D&D as its the most popular game and that whole Open Game License thingie.

Stuff like OSRIC and Labyrinth Lord are pretty much nearly exact copies of AD&D and basic D&D while games like X-Plorers, Encounter Critical, and the like are more style similar to older games or take more liberties to improve the game. (X Plorers is a personal favorite, being "What if instead of being into fantasy, Gygax & Arneson were Sci Fi fans"?)

hi Jason, welcome! We have one group started right now and I'm thinking we have enough new members that we could form a second separate group. Rich seems like he might be amenable to DMing another group.

Shadowrun would be a blast to play again.

Welcome, Jason! If you're interested in playing, keep your eye posted as the "Fall Season" is kicking off. If you'd like to run something, feel free to recruit and I can set you as an "event host". Shadowrun would be fun to play again! Look up Hopkinton Board Game group for frequent Arkham Horror opportunities.