Zig Zag, a game by Anthony Crowther in collaboration with author David Bishop, has you "speeding down narrow passageways of the Matrix of Zog, somewhere in the 12th dimension", as quoted from the instructions.
Basically what this means is that you control a triangle-shaped ship in an isometric-view screen, and you have to try and find eight "crystals of Zog" in order to complete the game. To do this, you can control your ship to move left, right, up and down in order to shoot enemy ships coming towards you or avoid traps and walls. However, your ship can't change its forward momentum - to do this, you have to fly into a prism found on the floor of various intersections of the corridor. The angle of the triangle determines which direction your ship will rotate. Hitting the "flat" end of a triangle will merely bounce your ship into a 180-degree u-turn; but hitting the angled side will rotate the ship 90 degrees. These triangles are necessary to get you through the maze of corridors.
Along the way, you will also encounter switches that will remove walls that would otherwise bar your way to another part of the map, or add prisms that will get you moving in the right direction. Beware though, switches are "toggles", so if you go over a switch that has just removed a wall, going over it again will bring the wall back. Switches are either on the floor (which you merely skim over), or on a wall (which you have to fire at).
In some areas of the map, there are "shop zones" that you can fly into. This brings up a shop screen where you can "purchase" items (with accumulated points) that will help you get further in the game. Items include U-Turns (which will immediately flip your ship 180 degrees), Zapps (kills all aliens on the screen), Maps (shows you maps of where you've already visited - not where you're going!), Extra lives, Missiles (increases your shot rate), Shields (prevents alien collision/shot damage), Raisers (forces aliens in the air, so you can fly below them), and Infrared vision (for seeing in dark areas of the map).
Selecting these items requires you to press space on the keyboard so that the item (shown in a scrolling area at the top of the screen) is highlighted, then pressing fire.
While flying around, there are also Save Zones, which will take you back to the main screen with an added code, that you can enter when starting a new game without having to begin at the very start. Very handy, as this is a big game! But remember to jot the codes down for later use! One item you get at the start is "Home James", which takes you immediately back to the last Save Zone you have visited (or the start of the game if you have not found one yet). Useful if you know you've missed a crystal and want to navigate an area again.
Unfortunately, there are other "zones" - like a Death Zone, which results in the instant loss of a life. There are also Time Locks - basically, all time locks are open for 144 minutes (2 hours 24 minutes), but once that has passed, the locks close. You can still finish the game, but it's much, much harder!
You start with three lives, and lose a life if hit my an alien or its weaponry, and you can claim back lives by purchasing them in a Shop Zone.
The game itself is very well-made; the isometric view has been expertly programmed and is very smooth. There is the odd glitch when the ship rotates or flips, but it's forgiveable and also works in your favour, by giving you a couple of moments' breather. The ship graphic is very simple - a flying triangle - but it actually works well with the triangular look of the prisms and overall 3D look. The aliens are cute, cuddly, colourful - and very deadly - and are easy to identify so that you can take immediate action. In-game sound can either be sound effects (which are minimal but effective) or a music track (which is typical WE M.U.S.I.C. fodder that you find your head bobbing to while trying to get around the maze).
If you like your games to have some mental capacity, along with the usual physical shoot 'em up, then Zig Zag has a lot to offer. An interesting idea for a game that has been professionaly executed by the arguable genius that is Tony Crowther.
