There are a few options: the game Lodge itself has rooms and fancy cabins, and the campgrounds on site and close by have campsites and little rustic cabins. Both of these options have different reservation procedures. State game lodge rooms are available If you want to book this option call +1 605-255-4772 . Campsites at the lodge campground and campgrounds close by open for reservations 365 days in advance at 7am. Follow the link attached below ASAP to have the best chance of reserving a camping spot or small cabin. They tend to go quickly. I highly recommend if you know that you will be attending to reserve a spot as soon as the reservations open. Worst case scenario, the game Lodge and campgrounds fill up and you find some off-the-map camping nearby or a hotel in the neighborhood towns, but know that Memorial Day weekend is very busy in the Black Hills and searching for a place last minute is not recommended. Please don't hesitate to reach out if you have any questions or concerns!
# for Lodge Reservation (can reserve now until July 10th): +1 605-255-4772
Link for campsite and small cabin reservations:
https://gfp.sd.gov/csp-campgrounds/