This mod is great--solid, engaging, thorough, and vibrant. An entire world is constructed quite literally from the ground up, out of legos. Unlike most platform games, which feature mysterious floating platforms, every piece of land the player stands on in Lego Keen is either firmly rooted to the ground, or visibly suspended in some fashion. This makes for a deep, believable world that envelops the player from square one.
Granted, a world of legos can be rather cold and uncaring--and visually mundane--but Lego Keen does a good job of adding fuel to its fire. Every few levels, something new is added to keep the player alert. Vanishing blocks, optional routes, out-of-the-way goodies, and lots of rewards for backtracking help keep each level alive as long as possible... at times, even too long. The levels in this game border on massive, and getting lost in this blocky realmn isn't hard to do. Playing the game repeatedly helps to alleviate this problem, but initially a player may find themselves wandering aimlessly, trying to remember where the Green door was...