Since this scenario is extremely rainy, you should start off the scenario by building an Information Kiosk. Not only will it lower the chances of guests getting lost, it will also help keep them happy in the rain
(Tip: You can charge $20.00 for umbrellas, and the guests do not care. Use this tip if you are short on money).Once all that is done, build mainly indoor and underground rides, these rides will attract guests during the rain. Try to make indoor rides (like the Merry-Go-Round, Monorail, Car Rides with pickup truck cars, etc.) outdoors, filling the space outside of the pyramid.
To build tracked rides completely inside the pyramid, start building outside, tunnel in the pyramid and then remove the outside part. A tracked ride needs at least 40% of the track underground to count as indoor ride. Do not forget to build stalls and bathrooms for the guests.