The only way to eradicate the disease is to pilot a nano probe to blast rogue cells while simultaneously destroying the pathogen's "pseudo-DNA." The handiest way to do that, as it turns out, is to match up all the pretty colors.
Unlike Zuma, however, the relentless march of colored cubes is not your only concern. There's also a horde of microorganisms that will stop at nothing to destroy your nano probe. Luckily, zapping these micro-critters yields power-ups for the probe and, more importantly, cubes to launch into the pseudo-DNA chain. Matching up three or more cubes of the same color will cause them to explode, eventually destabilizing the psuedo-DNA chain and getting you one step closer to eradicating the disease. (Or, to put it in game terms: You have to reach a certain score to clear a level.)
Once the basics sink in, Transcripted becomes a hectic juggling act as you try to ward off enemies while simultaneously concentrating on destroying the chain. I've never gotten a chance to become too comfortable, either, as Transcripted continues to add layers of new mechanics and different types of enemies. A couple of hours into the campaign and I'm no longer just matching colors. I'm consuming cubes to remove toxins from my probe, or I'm "hacking" certain enemies to reveal special blocks that increase my score. In an interesting (and difficult) twist, some levels actually have you defending the chain from enemies.
Mixing gameplay concepts doesn't always pay off (to which countless poorly implemented "stealth" levels can attest), but in the case of Transcripted, the blending of puzzle mechanics and classic shooting comes off with nary a hitch. For anyone with $10 to spare, it's a great way to flex those mental muscles and relieve that itchy trigger finger.