Looks like expansion packs. From the Google Play page: "PLEASE NOTE: Additional content for RollerCoaster Tycoon Classic is available via In-App Purchase, specifically the three expansion packs: Wacky Worlds, Time Twister and Toolkit. The expansion packs are the ONLY content that require an In-App Purchase and In-App Purchases are not used anywhere else in the game."

Actually, the toolkit as an IAP really pissed me off. That's the best way to design coasters.

I didn’t realise there were any! I just checked: it’s 3 expansion packs with I assume more rides and campaigns.

The game already comes with 95 campaigns that you have to unlock gradually. They’re quite varied in terms of style and goals. I’ve completed 17 so far. I bought the game last December, so I still have lots of content to play with…

It's a shame because the game uses IAP for a good reason.

But I don't blame you for being reticent, I am too.

I have the game on both iOS and Android - and the only paid purchases in it are the expansion packs, the game never ever asks you to buy them, but if you do it unlocks the content of the expansion packs, so exactly like with the original game. They are the best IAP I have seen so far.