Indoor cycling apps have exploded. Here are the ones worth your time.

Zwift
The most popular. Virtual world, avatars, group rides, races. Gamified cycling. Works great with smart trainers.
Social element is strong. See friends riding, join them mid-session. Keeps indoor training interesting.
$15/month. Worth it for winter riders.
TrainerRoad
Structured workouts, no games. AI adjusts your plan as you go. Serious training tool.
Podcast during intervals keeps you sane. No scenery to distract. Just the work.
Best for goal-oriented riders. Racing, events, specific fitness targets.
Rouvy
Real video of actual roads. Ride famous climbs from your basement. Alpe d’Huez, Stelvio, whatever.
AR mode overlays avatars on real footage. Weird but effective. Less cartoon-y than Zwift.
IndieVelo
Free alternative to Zwift. Smaller community but growing. Racing focus.
Worth trying if subscription costs bother you.
Peloton Digital
Guided classes without the Peloton bike. Works with any setup. Instructor-led.
Good for people who need someone yelling at them to push harder.
My Setup
Zwift for social rides and base training. TrainerRoad for structured intervals. Switch depending on the goal for that day.