At its core, On the Deck feels like a classic gravity-tilt-drop puzzle, only instead of guiding a ball into a hole, you have to manipulate tumbling passengers and cargo into doors, hatches, or just keep them onboard and out of danger. Controlling a ship or raft is deceptively simple — just click and drag left or right to bob each side of your craft up or down. You can also open and close hatches and doors by clicking them, which becomes critical on later levels. Some levels have you controlling a ship's bow and stern, while others involve listing the port and starboard sides back and forth. The real challenge comes from the fact that each floating craft is on a moving sea with huge swells that get worse over time.
In addition to the bobbing waves, On the Deck has various types of characters and obstacles to contend with in the game. The main characters are a series of boogying, Titanic-era sailors and ladies you generally have to save. There are also nefarious gangsters on board, as well as vicious giant crabs, hungry sharks, and deadly mines. Cargo includes different shaped boxes and rolling barrels, plus lifeboats and a few old-timey cars.
Make no mistake, On the Deck may sound simple, but it is tough. Addictingly tough. Some levels are pretty straightforward, while others will have you pulling out your hair trying to accomplish seemingly simple tasks. Mastery of the game requires a good feel for the rhythm of the bobbing sea, nimble manipulation of the decks to flip characters, and good timing to have sailors and ladies slide past deadly obstacles. Some of the hardest stages merely require you to keep a stack of cargo afloat for 30 seconds, and just when you think you've got it, you watch helplessly as the stack comes apart despite your heroic efforts to counter a large swell. Frustrating? Perhaps. But darn it if you don't keep replaying until you get it right.
On the Deck is quite fun despite its tough challenge. Its colorful artwork and folksy guitar jazz gives the game a nifty personality, and its varied, ample levels will keep you occupied for a good while longer than most casual Flash games. So grab your Dramamine pills, strap on a life vest, and hang on for dear life as you tackle this tricky nautical puzzler.