Skulls+Robots+Space=Fun
Gameplay:
Life Force and Gradius are probably the closest games to compare Abadox to: you are in space, you shoot stuff, get powerups, and kill the boss at the end of each level. Except in Abadox, you are actually inside a giant parasite planet. The enemies themselves are pretty varied and range from skulls, to giant geckos, to robots, and yes, even giant robotic skulls that launch brains at you when they die. Almost no enemy in the game simply moves in a straight line; each has it's own way of attacking so the game never gets old. Bosses, while definitely just as strange and varied as normal enemies, are not as impressive. Almost every boss in the game is attached to a wall or simply doesn't move. While many of the bosses shoot a large amount of bullets at you, there is usually safe spot where you can just hide until you move to get one or two hits in before going back, so boss fights tend to be boring. As a final note on boss fights, several of the bosses can be killed within two seconds if you know what part of the screen it appears in and just rapidly shoot almost any type of gun at it.
The level design in Abadox is also slightly strange. The game is divided into 6 levels with a 7th level at the end which is just the typical escape level where you need to dodge the walls. Every level can generally be divided into two decently long sections with a midboss. These sections can be incredibly different from one another so it really feels like there are 12 levels instead of 6. Perhaps the most interesting aspect though is the direction of the levels. In most games you usually go from left to right or from bottom to top in every level with maybe one level heading in the opposite direction. However, in Abadox levels 1, 3, and 5 are scrolling horizontally from left to right while levels 2, 4, and 6 scroll vertically. The vertical levels may take some getting used to because you actually start at the top and go down. The first few levels seem completely organic with flesh as the ground, flying eyeballs, teeth, and many other oddities. However, the later levels combine machinery and robots with the organic stuff while level 5 seems to be a type of factory with nothing but different types of robots. Although the level design is great, your 'ship' is not. Instead of controlling a ship, you control some guy in what appears to be a really weird looking yellowish spacesuit. Against all logic, he actually takes up more room than spaceships take up in similar games. This makes it slightly harder to dodge bullets and to navigate through some of the more narrow levels. Although the game gives out a healthy supply of powerups, they tend to feel more like a necessity than like a really helpful upgrade. By this I mean you will move extremely slow until you get a speed powerup and it can prove impossible to dodge some bullets if you miss speedup. Weapon upgrades help a lot as well and while it is possibly to complete a level with the standard gun, boss fights will take a painfully long time if you don't have an upgrade. Overall, the level design, variety, and difficulty are all nearly perfect, but easy and long boss battles, a really large sprite for your character, and being horribly weak (even more so than in most games of the genre) without powerups brings down the gameplay a little.
Graphics:
The graphics of the game are nice. The wide variety of enemies is a nice refreshment from the standard "ship A, Ship A recolor, Ship A recolor with bigger gun" found in similar games. The environment fits the idea of "you are inside a giant living planet" nicely and tends to be creepy without being disturbing. Some of the more robotic levels later in the game don't really feel like they fit the game, but they do nothing to ruin it. Pretty much all the enemies are where they should be with the flying eyeballs in the organic levels, the robots in the mechanical levels, and the robot brains in the factory/organic levels. However, for some of the enemies it can be hard to make out just what exactly they are supposed to look like and some of them feel like they don't belong (the final boss for example spits out odd looking ghosts they look more like they belong in a haunted mansion game for kids than for a game where you go into a living planet). Despite the occasional out of place or just plain poorly made enemy, the graphics look great overall. Unfortunately, some of the graphics have actually been taken from other games and simply recolored. The giant teeth in the second part of level 1 are clearly from Life Force and the eye at the end of the tail of one of the bosses is almost definitely also from the brain boss in the first level of Life Force as well. I'm sure at least one or two more enemies are also from other games and some parts of the walls of the second part of level 2 look suspiciously like they are from Metroid, but overall the graphics are fairly well done.
Sound:
None of the music really stands out or is memorable in any way. The sound effects are also neither interesting nor annoying. None of the music is bad though and some of it is enjoyable, but none of it is above average.
Overall:
Abadox is a very enjoyable game. It is decently long and varied so it never feels repetitive. The challenge rating is decently high, although there are other games in the genre that are much much harder. There is also an infinite amount of continues so even people that didn't grow up on old NES games could probably still beat it with a decent amount of patience. The powerups aren't anything special and are just the standard laser/missiles/speed/multishot/ring upgrades found in nearly all shoot-em-ups. The uniqueness in the levels and enemies is where Abadox's true strength lies and makes for an interesting experience. Although it is very unlikely to be anyone's favorite game, Abadox is still a great game and is definitely worth a dollar or two if you find it.