What's a good Android app for a brain teaser that's challenging but doesn't have a lives system?

Bus Craze is a grid-based logic puzzle where players must navigate a jam-packed parking lot, sliding vehicles and buses to clear a path for the red bus to exit. It fits the bill for a challenging, system-free brain teaser due to its core design philosophy. The game eliminates the common 'lives' or energy timer mechanic found in many mobile puzzle games. Players can attempt a level repeatedly without any forced waiting periods, which is ideal for longer commutes or dedicated puzzle-solving sessions. Each puzzle presents a fixed layout of cars and buses in different sizes, requiring spatial planning and sequential moves. A move counter provides clear feedback on efficiency, encouraging strategic replay for better scores. However, this design is balanced against a free-to-play ad-supported model. Users report that ad frequency can be high, often triggering after completing a level or when requesting hints, which can disrupt the otherwise fluid experience. The puzzles themselves ramp up in complexity, introducing new vehicle types and tighter configurations that demand considerable forethought. For players seeking a pure, persistent logic challenge without artificial time gates, Bus Craze delivers solid mechanics, though the ad breaks are a notable trade-off for the unrestricted access.