The Blue Marlin is a fishing game developed and published by Hot-B for the NES platform.
Though the ultimate goal is to catch a large marlin, that's far from the only thing on the menu. Additional large, and small, game exist which can boost the score in order to proceed to the next area. The player navigates a small fishing vessel over limited ocean real estate with a lure trailing a little bit behind. In order to initiate a bite, the lure must hover over a swimming shadow in the water. However, if the boat itself drives over a shadow, the animal or animals will scatter.
There are several shadow types to contend with as well as other factors. The most common are the schools of fish which are what the marlin feed on. Follow a school of fish long enough, and a larger shadow could appear behind them which could be a marlin. When the large shadow does appear behind a school, the goal is to maneuver your vessel in a way that the lure is over the large shadow but the vessel isn't scaring the fish away. This can be done either by stopping completely in front of the school and hoping the fish don't bite, or by maneuvering the boat just in front of the fish and slowly moving until the large shadow bites.
In addition to those shadows, there are also whale shadows (which cannot be fished, obviously) and flocks of seagulls. Following either of these things tends to lead to a school of fish or even a lone large shadow.Though the large shadows are marlin-shaped, they aren't necessarily marlins. They can also be swordfish, tuna, or even a great white shark (which can be trouble because they take long to catch and aren't worth much, so they eat up your time)
Once a bit has been initiated, the player comes to another screen with a visual of the fisherman and a visual of the catch in the water( for fish, its just splashes, for any kind of marlin or sworddfish, its a large fin, and for a shark its a shark fin. Both marlins and sharks have their own music themes) in addition to a meter measuring the fish's strength as well as one measuring the tightness of the line.
The goal is to real in the fish without breaking the line. The player can both reel in and let out line in order to keep it from breaking and tire out the fish enough to reel it in. Typically the fight of the fish correlates with the size but some, like barracudas, can put up a lot of fight and turn out to be worthlessly small and timewasting. Once the time is up or a fish has been caught that is large enough to weigh in, the player will be returned to port.
If the biggest catch and others add up to enough points, the player will be promoted to the next area. There are nine areas total, with 3 open at the start and the next 3 opened after scoring enough points. It is not required to go to every port in order to complete the game.