Okay this is a big request but hear me out. How about implementing a new game where the viewers in your channel level up based on how long they've been watching and have commands to attack an "NPC" created by the streamer and your viewer's have to team up together to bring it down, kind of like the bank heist but a little more interactive and if they kill the NPC they walk away with more stream currency.
ex.
Bot:"Crowbar has spawned a lvl 11 Dragon, type !Joinparty to enter combat"
user1:!joinparty
user2:!joinparty
user3:!joinparty
user4:!joinparty
Bot: 4 users have grouped up to take on the dragon User1 is the highest level and is the party leader, commands are !attack, !defend, !heal, !run, !magic
User3:!attack
User1:!magic
User4:!run
User2:!attack
Bot: User 4(lvl 1) runs from combat successfully not taking any damage, User 2(lvl 4), User 3(lvl 7) successfully attack Dragon lvl 11 for 200 damage 400hp left, User 1(lvl 11) casts a fireball and kills Dragon lvl 11 rewarding 200 points to the party.