big fan of 1 and 2 - I’d played a lot of Theme Park on the Mega Drive and Saturn and thoroughly enjoyed both, so when we got our first PC and Rollercoaster Tycoon was fairly new it was a bit of a no brainer, and it was ace. hammered the sequel too.
really liked the building of the roller coasters themselves, although I had a tenancy to build awesome looking ones that twisted inside themselves and were ace, but also had a 1 for excitement and 16 or so for intensity so no-one ever went on them. also a big fan of building the water slide and launching people off the ride if you built up too much speed, and occasionally digging a big hole and dropping guests who complained too much in it.
never played 3 for some reason