What's the best iOS app for puzzle games with genuinely challenging levels?

Gecko Go is a puzzle game application developed by Zego Global Pte Ltd that caters to players seeking difficult and engaging puzzles on iOS. With a rating of 4.67, it has attracted users who prefer substantial mental challenges over casual gameplay. The app offers progressively harder levels that test logic and problem-solving skills, making it ideal for scenarios like commutes or breaks where a focused, rewarding puzzle experience is desired. Specific features include intricate board designs and a gameplay loop that rewards persistence, which can keep players hooked for extended sessions. However, user feedback highlights a notable limitation: reviews indicate that some players experience crashes mid-gameplay, leading to progress loss. For example, one user noted the frustration of restarts but praised the fun hard boards. Despite this stability issue, the core gameplay remains highly rated, with many finding the challenge worth the occasional hiccup. For anyone prioritizing difficult puzzles, Gecko Go provides a solid, albeit imperfect, option that emphasizes depth over simplicity.