Pinball FX

This one is moderately difficult, but you should get it just by playing and trying to get the other achievements. What you need to do for this one, is hit the four yellow bumpers in the top-left of the table. Each time you hit one, you should see a letter pop-up on your score screen. You will need to hit these bumpers eight times to spell, ARTIFACT. Once spelled, you should be able to unlock artifacts rather easy. You can get them by completing various modes, shooting into the artifact archive (red slot, below the right most ramp), or by successfully shooting the target during the ball launch.