Gradius takes place in space and has players travelling between game worlds, separated by outer space sequences. The action unfolds through horizontally scrolling stages with the ship having to dodge land formations and enemy fire, fighting threatening enemies along the way. Controlling Vic Viper, the franchise's iconic white and blue ship, things start off real slow, with only a basic weapon available: the bullet shooting cannon, used by holding down the A button or rapidly pressing it. Don't worry, though, ammo is, thankfully, unlimited. To increase firepower, one has to collect power capsules that are left behind by specifically coloured enemies, or formations thereof. There lies the distinctive aspect of Gradius -- its option bar at the bottom of the screen.
Collecting an orange capsule highlights the first additional power on the option bar. Pressing the B button will activate the then selected power. The first one, "Speed Up," will increase the speed of the ship. It can be selected multiple times (apparently indefinitely in the NES version), each one increasing the speed even more. Amassing too many of those can render it nearly uncontrollable, so caution should be taken, and in most situations two or three boosts are enough.
"Missile" gives the ship the ability to lay down missiles that will then "slide" on the ground until they crash into a wall in the scenery or explode on contact with any enemy unit. "Double" lets the ship shoot diagonally upwards in addition to the original shooting direction, "Laser" allows for shooting long lasers that destroy every enemy the beams come in contact with (technical limitations of the NES turned these long lasers from the Arcade version into shorter ones, though).
One of the most popular powers in the Gradius series is the "Option," also called "Multiple" in the Western Arcade versions. This produces energy balls that follow the ship's every movement and mimic the ship's actions, thus multiplying the fire power accordingly. Most versions of the game permit a maximum of four of those, but the NES version at hand caps it to only two. The last power is the shield (labelled with a question mark "?" on the option bar), which adds two blue star-shaped elements to the front of the ship, capable of blocking a set amount of incoming enemy bullets.
The more damage it takes, the smaller it becomes, before it finally turns orange and disappears with the next bullet it blocks. Finally, blue power capsules won't advance the highlighted power on the option bar, but will rather destroy every small enemy on the screen.
These powers will certainly quickly become a necessity as the game is painfully hard, and there are no continues. A cheat code that must be input at the Game Over screen gives another continue but your servitor here has (frustratingly) yet to manage to get it to work! Start off with three lives, scoring a lot of points grants some extra lives along the way. That being said, the 3DS Virtual Console version comes with the Quick Save function, which alleviates all sense of challenge and will make the play-through feel absolutely unrewarding as opposed to a true play-through, following the normal rules. Gradius is not particularly long, with only six stages, and it plays on a loop with no real ending sequence beyond a 'Congratulations' message after beating the final boss, so cheating will only make it even shorter and make players completely miss the point of the game, which is to overcome the difficult challenge on skills alone.
A cheat code that does work, however, is the famous Konami code: "Up, Up, Down, Down, Left, Right, Left, Right, B, A, Start." If performed while the game is paused, it will instantly grant two options -- missiles and the shield -- which are helpful for starting again after dying in a particularly difficult area. This trick can only be performed once per game, however, so saving it for when there is no other choice is advisable. Like other games of its time, Gradius comes with quite a bit of "hard to pull-off" secret tricks as well that will let the player skip entire stages. This adds a lot to the old-school charm of this game as it was designed to be talked about in special magazines at the time, and between players, at work or at school.
While perhaps not as visually stunning as its Arcade counterpart, Gradius on NES was a quite good looking game for 1986. Its infamous and utterly weird use of the Moai statues of Rapa Nui (Easter Island) as enemies and bosses has become a landmark in the history of video games, and while the NES version may lack the voice clip urging players to "shoot the core" every time a core ship appears on the screen, it's nothing short of 'classicness' and any self-respecting gamer who is a fan of the '80s must make sure he or she doesn't miss out on this game.