The GGJ is hardware and software agnostic, meaning we do not demand that you use any particular platform or technology to make the games for GGJ.
Each year however, we do have offers for jammers from our sponsors. See here for the latest list.
We also have a list compiled by the GGJ community with many suggestions.
Also check out our list of simple tools for those who might not have much technical experience to get started making games, especially good for new jammers or non technical attendees.
You might want to send out a reminder to your jammers to download and update their preferred tools before they get to the event, so as not to strain the shared internet connection!