Very nice, though could use a little work.
This game kept me entertained from beginning to end. There was plenty of variety in gameplay and it was easy enough that I did not need a 20 minute tutorial to figure out the controls. This combination is lacking in much of the other stuff out there.
Not to be hyper critical, but the music did suck. And it kept playing. I suppose since sound played no role in this game, I could have turned down the volume and listened to the radio, so this isn't a major problem.
Also, some of the controls were funny. I was able to walk through blocks and it was not always evident where the boulders would go when I pushed them. Visually, it appeared as though the boulder puzzles were to be played on a grid, but that's not the way it worked out when I played the next to last puzzle. In fact, I have no idea how I finished that puzzle other than dumb luck, which takes away some of the satisfaction from the accomplishment.
Criticisms aside, I liked the effort. I'm a huge fan of the Metal Gear Solid series, and your game captures some of its fun elements, and infuses it with a healthy dose of Zelda-like puzzling.
Good job on an enjoyable game.