I know these ideas have already been done but here are a few specific games. I used to go on Cadet camps for seven days and also have the most inconsistent wifi in the world. These are my friends' and my personal favourite activities.
-Card games - oh my gosh, these are the best bonding activity and an absolute favourite.
UNO is the best thing ever along with other games with a traditional deck such as Rummy, Black Jack and Tongue (it's quite weird but also hilarious) - here's how to play:
https://www.classicgamesandpuzzles.com/Tongue.html- Board games - best ones imo are Cluedo, Rummikub is a new fave, Scrabble unites all ages and Game of Life.
- Art - doing basic art like drawing, calligraphy or painting (watercolour is great) alone or with others is always fun.
-Quick games like 20 questions where you think of a celebrity or an individual everyone in the group/ pair knows and they have to guess who they are in 20 yes/no questions.
-Group games if you make some friends such as Mafia, Ninja, Murder Winks etc. - these may sound childish but they're still great imo
-Download some music for offline listening
-Learn a new skill or something super random. You could print out some resources to learn morse code, learn how to spin a pen between your fingers or phrases in foreign language for example. I'm a big fan of learning raps to popular songs so you could always download some songs and print the lyrics haha (recommendations = Super Bass, American Boy, Macklemore songs, etc.
)
-If all else fails, bring some HW. I always find motivation to do school work when I don't have to but find it hard to do it when I
do have to. You may be so bored you'll do it haha and you'll be grateful you did later !
I hope this helps! Have fun