Thirty years ago, America was invaded by little men from space. Little digital 8-bit men who marched across the screen, then lowered, reversed direction and sped up. I am, of course, referring to Space Invaders, which is celebrating its 30th anniversary this year. To celebrate, those pesky Space Invaders have returned and are invading the PSP in Space Invaders Extreme.

Space Invaders Extreme is not just the original game ported to the PSP; it's a celebration of the original game. Instead of dragging such a wonderful 8-bit game kicking and screaming into 3D, they left it in its 2D glory. However, the Invaders have evidently realized that they are only 2D and occasionally use this to their advantage by turning "sideways", leaving only a single line exposed to your gunfire. This game features the same 8-bit pixelated sprites found in Space Invaders, but plays with scale. In some rounds, you'll face large Invaders that are about the size of six or eight normal invaders. There are also tiny Invaders that appear in a block of four and all together take up the space of one Invader. At the end of each level, there is a fight against a boss Invader, which can be something like 35 times the size of a normal enemy, taking up almost an eighth of the screen.

Additionally, instead of a plain, black background as was found in the original version of Space Invaders, the Extreme version has wildly animated CG video playing in the background. If you find this feature too distracting, you can adjust the brightness of the background or even turn the background off in the Options menu.

The sounds of the original Space Invaders are clearly identifiable in Space Invaders Extreme, but not necessarily where you might expect them. You'll here old, familiar sounds when you make selections in the menus, as well as when you're shooting enemies in-game. The music in Extreme is a tribute to the original, again, a celebration of the original and modernized variations on the theme. In layman's terms, it's fast, pumping dance-ish music with the familiar four note progression (thinking of the bass notes that used to play as the Invaders - you remember... "bomp, bomp, bomp, bomp..." ...basically the first four notes in the base line from "Pink Elephants on Parade.") They take that short progression and then simply go crazy. It's a very adrenaline-filled score that helps add to the excitement of the game.

First of all, I'd like to applaud Square Enix and Taito's handling of Space Invaders Extreme. Typically, arcade games either get ported directly to a system, offering a way to make a quick dollar off of fans or they over-modernize a perfectly good (or great) 8-bit game that is genius in its simplicity by blowing it up into some strange new 3D version of itself and change the way it plays completely, leaving a game that is, typically, pointless to anyone who wasn't familiar with the original game and an insult to anyone who was. Space Invaders Extreme, by contrast, snazzed up the visual presentation a bit, but kept the 2D, pixelated graphics we all know and love.

One way they did bring Space Invaders Extreme kicking and screaming into the present is with the addition of an ad-hoc wireless multiplayer mode. How exactly do you have a two-player version of Space Invaders, you might ask? Much in the same way that you have a versus game of Tetris. Basically, the more Invaders you shoot, the more you send over for your opponent to deal with. I'm sad to see that it's only ad-hoc; I wish I could play against someone online from wherever I happen to be, but the multiplayer game itself is loads of fun.

"Easy to play but hard to master." This is the holy grail of games. This is what makes a classic. Space Invaders Extreme took quite a chance by changing anything in Space Invaders, but they also made their changes carefully. As a result, Space Invaders Extreme is a delight to play. It is (relatively) easy to play, but it provides a good deal of challenge, especially as you work your way through the various levels of the game.

Additionally, as you progress, you work your way through a tiered series of levels. Each time you proceed, you're given a choice of proceeding to a hard level or an easy level. In this way, you can tailor your play-through based on how difficult you find the game.

If you find certain levels to be keeping you from progressing in the Arcade mode, you can play a single stage that you have previously completed in the Arcade mode by selecting Stage Mode. Also, you can always return to the Arcade mode and continue your previous game - a feature I greatly appreciated... and put to good use.

Another good way to practice your skills is against a friend in the Ad-Hoc mode. If you're not within wireless range of a friend with Space Invaders Extreme, you can choose the Practice item in the Multiplayer menu. This allows you to play a multiplayer game against the computer - a nice way to get familiar with the game mechanics of this mode and to plan strategies and try them out.

They have treated the Space Invaders license with the same respect that M&M Mars treats the Snickers Bar. There is a recipe, and it works. Any Snickers variation they produce follows that recipe and merely adds or replaces one ingredient. Almond Snickers replaces the peanuts with almonds. Snickers ice-cream bar adds ice-cream. Dark chocolate Snickers merely switches the chocolate from milk chocolate to dark chocolate. In this way, you get a slight twist on the concept, but the same great taste is still there. Space Invaders Extreme takes the same care with the Space Invaders license. There are new game mechanics. Things are changed. But not all at once. There are new enemies: big enemies, small enemies, enemies with shields of different types. There are differences between rounds: sometimes enemies simply move down the screen, slowly, while at other times, the left half and the right half move independently of each other. There are different power-ups: a very powerful, but short-lived laser weapon upgrade, a bomb weapon upgrade, a wide-shot weapon upgrade and a shield. There are a variety of different enemy mother-ships, with different scores and effects. However, at its heart, Space Invaders Extreme is Space Invaders, providing the same fast-shooting, missile-dodging excitement it did 30 years ago.