Alien Crush is an old console pinball game--it offers you pinball, aliens, and a bit of crushing.
Like with most old games, the controls are pretty simple. You have buttons for the right and left flippers, a button which allows you to shake the table, and--of course--a button for pausing the game.
I really like the music. Given the age of the game and that I first played it in 2007--no nostalgia attached--I'm surprised it's held up so well.
The graphics are old, to be sure, but adequate. I never wondered at a spot on the board and asked myself "Now what is that supposed to be?" The graphics do what they need to do for the game--show you pinball, aliens, and the crushing thereof.
The one glaring problem I have with the game is that the ball will sometimes bounce around, quickly, between the bottom section of the upper board and the top section of the lower board. The result is the screen rapidly flashing from one display to the other, until the ball decides where it really wants to go. This actually hurts my eyes a bit, but not so much as to, y'know, never play the game again. The effect seems worst while playing on slow speed.
I'd say Alien Crush is a decent old game, with the keyword being old. It's not terribly deep, there aren't unlockables, nor is there any special goal to work toward--it's just pinball. Well, pinball with crushable aliens. It's pretty much face value, so if you check out a game play video on Nintendo.com or Youtube and like what you see, then chances are this is $6 well-spent. If you prefer your games more involved or goal-oriented, then I'd suggest you look toward other titles.