We found that by taking our couch cushions off and stacking them we could build a little climbing course. My 15m old has also been having fun with my 3.5y old's rody horse. We also let him climb the building's stairs for fun.

pikler triangle! it folds up, it's super versatile, and most children continues to play with it for YEARS

Check out the Jungle Jumparoo. Your child is a little young for it but best toy I’ve ever owned. The smaller one works indoors.

https://www.amazon.com/Maxim-Enterprise-INC-Wooden-Tunnel/dp/B00FB7ZCTQ/ref=mp_s_a_1_1?dchild=1&keywords=collapsible+tunnel+for+toddlers&qid=1595975104&refinements=p_85%3A2470955011&rnid=2470954011&rps=1&sprefix=collapsible+tunnel&sr=8-1

https://www.amazon.com/Franklin-Sports-Flexible-Soccer-Cones/dp/B003KV79RS/ref=mp_s_a_1_3?dchild=1&keywords=toddler+cones&qid=1595975511&refinements=p_85%3A2470955011&rnid=2470954011&rps=1&sr=8-3

https://www.amazon.com/Yes4All-Rocky-Balance-Pods-Set/dp/B085C9CCFZ/ref=mp_s_a_1_8?dchild=1&keywords=toddler+balance+step&qid=1595975885&refinements=p_85%3A2470955011&rnid=2470954011&rps=1&sr=8-8

https://www.amazon.com/DEVEBOR-Balance-%EF%BC%8CBalance-Training-Exercise/dp/B07FX7DQMG/ref=mp_s_a_1_4?dchild=1&keywords=toddler+balance+board&qid=1595975926&refinements=p_85%3A2470955011&rnid=2470954011&rps=1&sprefix=toddler+balance+&sr=8-4

https://www.amazon.com/Flybar-Jumper-Toddlers-Durable-Supports/dp/B00WTCN9PU/ref=mp_s_a_1_42?dchild=1&keywords=toddler+curved+balance+board&qid=1595976099&refinements=p_85%3A2470955011&rnid=2470954011&rps=1&sr=8-42

What about something like this that folds up out of the way?

https://ezplaytoys.com/collections/new-toys/products/panda-playground

Or a Pikler triangle? Also foldable

https://www.etsy.com/listing/732621880/foldable-pikler-triangle-solid-with-ramp?gpla=1&gao=1&&utm_source=google&utm_medium=cpc&utm_campaign=shopping_us_ts1-a-toys_and_games-toys-baby_and_toddler_toys-other&utm_custom1=c75fb0a0-86e4-45cd-a6c8-dc3fe83a99f4&utm_content=go_1844702535_66522782061_346363904862_pla-316238738045_c__732621880&utm_custom2=1844702535&gclid=EAIaIQobChMIlvG2o9jw6gIVhZyzCh0FzwYLEAQYASABEgIg7PD_BwE

My 18 month old is currently climbing all over everything he can get his hands on. I was debating getting him a climbing toy to direct that energy. However I live in a relatively small apartment, so something I can easily put away is a must. Any recommendations? I was looking at those sectional foam stairs/tunnel type thing but wasn't sure if that would work.