Best for those who don't already own, or never played the first
How do you improve something that is essentially perfect? Well, in the case of Space Invaders, you just add some flashy, psychedelic visuals, and make a few changes to the gameplay. That may have worked for the original Space Invaders Extreme, but for its sequel, Space Invaders Extreme 2, it just feels old.
Instead of trying to build upon the foundation of its predecessor, Space Invaders Extreme 2 simply makes a couple of very small changes to the gameplay, and adds a few new backgrounds, making this feel more like an expansion pack with new visual effects instead of a full-on sequel with new modes or refined gameplay.
In fact, the only new addition is Super Fever Mode -- a newer, slightly crazier version of the normal Fever Mode from the original. It's a minuscule addition that doesn't add anything of note, as the differences between the two states of that mode are extremely small.
Both modes have the same task: defeat groups of enemies to make them drop items that net you points. The bottom screen contains the usual assortment of invaders, and the top screen has UFOs. In normal Fever Mode, only the gold-hued invaders on the bottom screen drop the aforementioned items. In Super Fever Mode, the UFOs drop them as well.
That's about it, aside from how the two are activated (Fever Mode simply requires to beat a mid-level challenge, and Super Fever Mode requires you to somehow get a "Bingo" on the board located on the top screen).
They do add a small element of strategy, for in order to activate the mid-level challenges you must defeat either eight enemies of the same color or four of one color and four of another, but it hardly has any meaningful impact on the game.
The rest of the game remains unchanged. Everything from the first game -- fighting off waves of multi-colored invaders that slowly get closer to you, whilst attempting to complete mid-level challenges that appear out of nowhere -- is still here, and still fun. But it's not as fresh as it was in the original, making it feel like you've done it all before (and assuming you played the original, you probably have).
The game also has a tacked-on multiplayer mode for up to two players locally or online that pits two players against each other in... a game of Space Invaders. It's bore to play, and doesn't ever feel like you're actually going up against another player since there's no way to interact with your opponent in some way. If it weren't for the top screen showing the other players activity, it wouldn't feel anything like a multiplayer mode.
The multiplayer can be played online, but I was unable to find anyone online whenever I tried. So I'm taking that to mean the online community is dead. Leaderboards also make an appearance here and are a nice addition, but it's not enough of an incentive to keep playing.
Newcomers should enjoy the new take on this old classic for its the neon visuals that give the game a great sense of style, and the upbeat techno music that complements the visual style nicely. But for the rest of us, all we get is an experience that is essentially a repackaged version of the original.
If you already own the original, go play that instead.