About 36 hours of total play time, and I finally beat Tri: Of Friendship and Madness. Though the game is heavily derivative of Portal, it quickly goes in its own direction with the puzzles.
After a tutorial level, you're given a Tri, a device that makes triangles which you can use to bridge gaps and make pathways up the walls and along the ceiling. In later levels you use them to reflect light beams, guide lasers, and more! And then you are told to find the fox.
The first ten levels or so are tantalizing and brain-teasing enough, and then level 11 hits. From 11 to the end, the puzzles are MEAN! Multi-step, thinking outside the box, taking these game mechanics and stretching what you can do with them to the very edge of reason! There are some strange maneuvers you have to pull off, and figuring out what you have to do requires paying close attention to the environment.
The puzzles are mean in a good way. Everything you need to solve them is right in front of you. Learning to recognize what is possible with all these devices, how they behave, and how you must use the triangles to make them work together is mind-stretching. This is not for casual players, and I like that.
These are expertly-designed levels. Nothing is unfair, nothing is obtuse. I finished the game without consulting a walkthrough, or taking any hints, and I am proud to have figured everything out by myself. Those last two levels are a doozy--each taking me two sittings to figure out--but everything is logical.
The story is a bit thin. It's told between levels instead of experienced as you progress, but that's a minor gripe. I can see how the foxes went mad with this kind of freedom of movement. I almost went mad figuring this stuff out. Forget thinking with portals. Thinking with Tris will kick your butt!
I have only one real complaint: the music. It's not bad music, but the way it's used is. Each level has a segment of music which lasts one to two minutes, and this clip plays over and over and over, with about 30 seconds of silence in between. On some levels, I heard the same 1-minute loop a hundred times, and it became so tiresome I often switched off the music and played my own. The soundtrack is so much better when it's not broken up and looped. I bought it as a symbol of my triumph!
Other than this flaw, it's a wonderful game. Superbly crafted levels, excellent use of its game mechanic, and foxes!