Neon Abyss

This CAN be gotten in the first level, but requires some lucky room generation. You just have to kill yourself 9 times using environmental hazards. These include spike-floors, spike-traps, and swinging spike-balls. Laser doors DO work towards the achievement. The wisdom crystals (purple crystals you feed crystals to, but turn red when you shoot them), spiked chests, or explosive barrels DO NOT count towards the achievement.

The fastest way to grind would be to jump into the abyss, run around the first couple of rooms to find a spike floor (most common in early stages), stand in the spikes to let them kill you, then repeat. If they aren't there in the first couple of rooms, I'd suggest beating the first level boss and trying to advance. Traps pop up more often in later levels, so you're doing yourself no favors by killing yourself from enemies and trying level 1 again. The swinging spike balls and laser doors don't seem to appear until later. If you are lucky enough to get a laser door, simply run into and out of the room that is separated by the lasers. Once you're through, they only regenerate once you get a certain distance on the other side.