Space Invaders

Space Invaders, colloquially known as Space Invaders '99 or by it's Japanese title Space Invaders X, blends together many components to create an indelible experience that can be replayed over and over.

The gameplay and controls are more or less what one would expect from the grandfather of the shoot-em-up genre. You move left and right, shoot at aliens and dodge the bombs they drop, however it doesn't stop there. The aliens get faster the less there are on screen, When only one is left, it madly dash from left to right all the while going on a mad bombing run.

First off to discuss is the way the shields work.
Unlike the original 1978 game, the guards don't crumble with each hit but instead have a set amount of hit points shown visually by the shield growing darker the closer it gets to being destroyed. Rather than these shields being static objects, however, any time a player shoots them, they lose health but also slowly inch up the screen. The max distance is about half way, or depending on how much health the shield had before. This little trick can be used to catch the last alien in a wave.

Another wonderful addition this game made was expanding the incentive to shoot down the mother ships that pass above the alien waves from time to time.

When destroyed, they will drop one of four possible Power-Ups: Double-Shot, Tank Shield, Time Stop, and Special Attack.

A Special Attack is a powerful one-shot granted by killing four of the same kind of aliens in a row, but be careful not to go off streak as this will reset the counter.

There are four basic alien types, and with them four recurring specials:

Red ~ Super Missile, flies in a straight path upwards and cuts through multiple enemies. Useful for wiping columns.

Blue ~ Horizontal Left Missile, flies upwards until hitting an alien where it will make a sharp 90 degree turn left and wipe out a row.

Green ~ Horizontal Right Missile, same as H. Left but it goes right.

Yellow ~ Diagonal Split Missile, flies upwards until hitting an alien where it will split into two diagonal projectiles at 45 and -45 degrees to blow a V shape through the alien wave

There are eight worlds on Normal Difficulty, ten on Expert and the unlockable Maniacal. Each lasts ten waves and ends in a unique boss fight that strips you of your special attack so you only have your basic attack against the boss.

In addition, each planet (except for Pluto) also has it's own unique alien with it's own abilities, and of course with that naturally comes a unique Special Attack.

That's all the pros I can think of.
Let's get to the cons.

One area where this game is pretty imbalanced is the Double Shot power-up. It does exactly what it sounds like, grants you an extra on-screen shot.

It's pretty useful and balanced against normal waves, but it makes a joke of almost every boss (most notably "Circle" on Saturn and "Turret" on Jupiter).

Except for that, honestly, the game is great fun and I heartily recommend it to casual gamers and arcade lovers.