An indoor ride is a categorization of ride in RCT and RCT2. Indoor rides attract guests when it is raining. The guests flock to the ride regardless of their intensity preference. On the other hand, outdoor rides have the opposite effect. Guests will say "I'm not riding ride "x" while it's raining." Tracked rides that are mostly indoors/underground, even with open cars/trains, will be considered as indoor rides.
Indoor rides on the original RCT
Below is a overview of all indoor rides on the original RCT, sorted by type of ride. This list assumes the rides aren't built underground. This list includes rides and vehicles that are only available in the expansion packs.
None of the rollercoasters are classified as indoor rides, unless they are built at least 40% underground.
None of the water rides are classified as indoor rides, unless they are built (partially) underground. Even using closed track on an entire Water Slide, won't make it an indoor ride.
All of the shops and stalls are continued to be used by the guests when it rains.
- When playing with the expansion packs, using a different style of ride entrance and exit (one that make it seem that a roof is built above the station platform) never makes a ride become an indoor ride.
Covered rides in RCT2
Below is a overview of all indoor rides on RollerCoaster Tycoon 2, sorted by type of ride. This list assumes the rides aren't built underground. This list includes rides and vehicles that are only available in the expansion packs.
No roller coaster is considered covered unless underground or enclosed by scenery. The only exception to this rule is the Yellow Taxi Coaster from the Wacky Worlds expansion pack, as its cars have a roof.
- No water ride is considered covered unless underground (impossible) or enclosed by scenery.
Literal "Indoor Rides"
In RCT2, any ride (including tracked rides) can be considered "covered" by guests through use of scenery pieces. Like RCT1, in which guests would ride tracked rides at least 40% underground, the same principal applies with scenery items (walls and roofs) in RCT2.
The roller coaster seen center of this image would be ridden by guests in the rain. There are also several enclosed flat rides. This technique will work with any ride that can be covered to a majority with scenery.