Super fun project!

Colors would be a nice place to start - greens, creams, blacks etc - there are fun modern/quirky riffs on the animal heads done by artists with cardboard etc (etsy could be a source)

a few things we had in our teen room: a round table and chairs for card games, poker as well as a spot too eat (i bought a solid oak set on facebook marketplace and sprayed it black)

we got a simple black fridge and tucked it next to a kitchen cart with a stainless steel counter and that was perfect for pizza boxes, sticky 2L bottles etc

we also put wifi enabled bulbs in the lamps so they could change the light color to whatever they wanted - that was weirdly a huge hit. plus a great wireless speaker they can all easily tap into

i am sure others will have lots of ideas

(and maybe some indoor/outdoor rugs to help ground the space?)

Have them tell you what they’d like included and try ChatGBT and provide a overall description. I requested “garage turned into a safari themed games room for kids and teens”. Then modify by adding more defined needs.

For instance, I was asked after the above was generated:

I'd work on the foundation of the room to work with out the safari theme so it can be changed out without much effort. Color Drenched in a rich earth color, wall and trim the same to allow the highlight/contrast to be the decor, not contrasting trim work.

Painted or stained wood... plywood and 1x4's can make great paneling features and look great stained or painted all one color. Don't for get great lighting.

as stated above, lots of great decor pieces available in paper mache or cardboard look elegant in a den like setting. Polished concrete floor. you may even be able to find some great leather furniture on marketplace or local charity shops. HAVE FUN!

I would rethink a safari theme at all. Ask the older kids since the young ones will grow up quickly and hopefully like some things the same as the older ones. Themed spaces rarely have longevity so keep whatever you do to a minimum witha good backdrop where a few elements can be changed over time

Sounds like a fun project!

It doesn't have to be a child focused Safari Theme:

with the right colors and materials you can create something relaxing and beautiful that can be enjoyed by any age group.