Descent II was released in 1996 and developed by Parallax Software. The game is the direct sequel to Descent which was released a year earlier and like its predecessor it is a six-degree-of-freedom flight combat game set in underground mines.
While on a quick look the game looks almost identical to its predecessor, differences in level design and a few new gadgets change the gameplay and flow a good bit. The first noticeable change are the new weapons, next to the basic laser, vulcan, spread, plasma and fusion weapons there are now essentially more powerful versions of each of those. The the gauss canon shoots explosive projectiles, the helix cannon has a bigger spread then the spread canon, the phoenix shoots reflect on walls and the omega weapon shoots kind of a lightning beam. The missiles got extended as well, next to the concussion, homing, smart and mega missiles are now flash missiles, which can blind players and enemies, guided missiles, which can be remote controlled by the player and earthshaker missiles, which provides a earth shaking explosion. The bombs get extended with super bombs, which explode into numerous projectiles.
The new non-weapon items include a set of headlights, that lights up the environment, but uses energy and an afterburner, that provides a quick boost for the players spaceship. The classic flares are still present. The most significant new item in Descent II is probably the guide bot, this little helper, which has to be found and freed at the start of each level, provides an invaluable navigation help. It is able to find energy centers, shield bonuses, hostages and mostly importantly the next needed key. The way it flies around and beeps gives it a very cutesy robot feel, somewhat similar to R2D2.
The enemies in the game are all new, but follow mostly similar design to what was present in the predecessor. The most notable change is that the enemies with homing missiles and vulcan cannons are now a good bit weaker, reducing the frustration they causes in the first Descent. The game however does add a few new annoying enemies types of its own, namely some of the bigger enemies break up into smaller ones on destruction, that are rather fast and hard to hit. The game also adds a special kind of enemy, the thief, this enemy is essentially an evil version of the guide bot. Like the guide bot it will follow you around the labyrinth like levels, but unlike the guide bot, it's not there to help you, but to steal items from you. The thief is extremely fast and will retret on an attack, thus he is extremely hard to hit and kill, which makes it all the more satisfying if one can lure him into a bomb trap.
The level design in Descent II is substantially more complex then in Descent, while the levels are still build up out of a series of deformed cubes, Descent II rarely uses just a single series of cubes to build a corridor, instead it frequently uses multiple cubes side by side to build a wider corridor with beveled edges. The levels are also a good bit more open and less claustrophobic. Descent II also adds some new elements to the level structure itself, while finding the blue, yellow and red keys still form the central part of a levels progression, the game adds plenty of switches, force fields and secret passages that are sometimes used to make progress, even with the help of the guide bot, a little less obvious. Light sources within a level are now destructible once shot.
The auto level functions continues to have the same problems as in the first Descent, namely it tries to align you to the walls of the cube you are in, not any kind of logical horizon of the room you are in. This in combination with the more complex room layout causes much more frustration then it did in the previous title as some rooms become essentially impossible to navigate properly as the ship will constantly try to rotate and thus it becomes more a fight with the controls then a fight with the enemies.
Overall Descent II is again, like its predecessor and its successor Descent 3, a bit of a mixed bag. The core gameplay is still as entertaining as ever and some of the new items make very welcome additions. The guide bot provides invaluable navigation help and makes traversing the levels much simpler without feeling like a cheap cheat and the afterburner makes an essential tool when it comes to dodging enemy homing missiles, as it allows you to cut them short and circle behind the enemies. The thief enemy also leads to some very exciting chases through the mazes and might require some planing and trap building to catch him. It is a type of enemy that I haven't really seen in any other games. Other additions like the new weapons however feel in large part kind of useless, as you simply end up with to many weapons and in turn don't bother to ever use most of them. The boss difficulty, again, is completely insane and the game also has more boss enemies then the previous part, leading to a lot of frustration and load and save cycles. The limited number of lives is still present, but like before won't really matter as load and save will keep take care of the retries.
Having more hidden things in levels is a welcome addition, but the puzzles that slow down the level progress can be a bit annoying, they are also largely build around trial and error, as the game doesn't really provide hints as to where a switch for a force field might be or what wall a switch might have opened up. The guide bot won't help in those situations, as he will simply respond with a "Can't reach XY" when a switch puzzle has to be solved before progressing. Switches are furthermore not marked on the auto-map, so finding them in the first place can often be a little tricky.
The more complex level design also isn't really a change for the better, as frequently they simply look a little ugly. The restriction to basic cubes in the first Descent meant that the levels could be navigated smoothly, the levels here often have you bump into corners and edges as the structure is less regular. Essentially the level end up feeling a little to random and don't really have the same flow as previously.
In the end the core problem with Descent II is that the longer you play it, the more annoying it gets. The first few levels are a ton of fun, but once you reached the last few you just want to get done with it, as the more difficult enemies and enemy placement spoils the flow of the game and leads to quicksaving at basically every corner.
As for what is the best game in the series, that's hard to tell, all of them have their great parts, but also their really frustrating ones. The first seven levels of the first Descent, the one from the shareware version, are probably the best Descent out there.