One of the finalists for Ludum Dare 20; Questling is an interesting puzzle game that will certainly give you a good challenge. The gameplay is similar to that of Psygnosis' iconic game, Lemmings. As mentioned, the game was designed as an entry for the Ludum Dare 20 Game Development competition. The tournament is aimed at urging indie game makers to create and develop a game in roughly 48 hours only. Each tournament has a theme that developers must follow and exhibit in their finished work. The game is available for free download right on the Ludum Dare website. The updated version that incorporates the soundtrack is also there.