Sims 4 recreation expansion / game pack

@Thefoodunicorn Wow, you have a lot of fun ideas there! To add my two cents worth, can I add my thumbs up on a few specifics?

• I would absolutely love to see ballet as an option. Especially as a physical/fitness option for children, as those are overly limited.
• As mentioned above, more fitness activities/items that will keep children fit and that are basegame. (Chunky kids can be tough to tone down.)
• I would love to have ballroom dancing! 
• Dancing classes would be fun... perhaps for kids on ballet and ballroom for adults? Nice prep for a wedding!
• Getting the pool table back would be awesome! I used to love getting a pool table for my Sims in past games if they had room and money for it, and they had so much fun with it!
• I'm not sure if this is what you mean by water slide, but a slide for the pool would be great! Also, having the ability to snap the toddler slide into the 'kiddy pool' and have it function properly after doing so would be wonderful!

A few things you may or may not be award of on your list that are in the game currently, though some need packs to add them:

• There is weight lifting in the game if you purchase one or more of the types of 'weights' machines.
• If you get one of the card tables they can play cards on that. Obviously this isn't poker specifically, but I though I'd mention that in case you hadn't seen it.
• There is a water slide of sorts in the 'Backyard Stuff' pack. Rather like a fancy 'Slip and Slide' (on the ground not in a pool). They love that!
• Pottery/sculpting... not really the same thing, but if you're not aware... there is a clay 'toy' in the kids stuff, and Sims of all ages are crazy for that thing! It can be a distraction that annoys some players as they will oftentimes pop it into their personal inventory and pull it out randomly to 'play with', but I find it is super useful to my Sims as an entertainment, mood lift, and inspiration when they need it, and sometimes they will randomly and autonomously 'fix' their mood or fun need on the spot by pulling it out. Win-win in my book!
• You mentioned stretching. If you don't have it, 'stretching' reminds me of some of the yoga moves. If you get the Spa Day pack it adds yoga, which is a really nice option.
• There are ping-pong tables in the game currently. They come with the Discover University pack. It would be nice to have a basic one in basegame, though.
• 'Sketching' may be somewhat addressed by doing figure drawing, if you haven't tried that out? It's one of the options, I think, with the painting easel. There are also craft tables for kids in a couple of packs, and one basegame. Again, not the same things exactly, but I thought I'd mention it in case you haven't seen them.
• Also, not quite the same as 'Photo Booth', but I used this as such for a wedding very successfully... there is photo studio that comes with 'Get to Work' that can be used this way. You need to run it with a Sim.