This game is either mesmerizing or nauseating depending on your personal preferences and your easy-dizziness factor.
I discovered the game when I opened the Droid Market and it was the first recommended app. I started to read the reviews and had to scroll down many pages before I found a review that wasn't five stars.
I downloaded the game and began to play. Very simple goal: get as far as you can into the tunnel.
When you become proficient at the game, which I am not, I believe there are ways to acquire more energy and weapons, but I don't have a clue. I'll let you know if I ever reach a level of expertise beyond the "Oh my god! Oh my god! Watch out! Watch out! Oh crap!" stage.
All I know is that it's a fun diversion for wasting a little time as I try to beat my own personal high score. (Too embarrassed to tell you what that is.)
Speedex 3 d will take up 4.79 meg on your Droid. Of course, one of the fun things about Smartphones is you can download apps, check them out and just delete them if you don't like them.