Some of the most impressive games you can get these days are the virtual reality style 3D adventures like Mercenary 3. You know, where your alter-ego is free to wander through and round the back of a complete world rendered in three dimensions. Programming such wonders isn't easy, and until recently, was out of reach of all but the most competent programmers. Then, in the summer of 1991, out came 3D Construction Kit, a dedicated utility to create 3D worlds. Since then, Domark have been beavering away and have produced 3D Construction Kit for you to play with.

The basic format of the program is unchanged. The editor is used to create a world divided up into areas, each filled with objects built from a series of primitives. These objects can have attributes assigned to them - they can move about, appear or disappear, change colour and do nasty things to you.

Once you've populated your world, it's time to let people loose in it. You can control the viewpoint and movements abilities of the players - they can walk or fly, shoot back at things or wander around aimlessly bumping into things.

After long hours, your work can be then compiled into a standalone program and distributed to universal praise from your mum.

3D Construction Kit 2 doesn't write good games for you but it does bring the 3D world within reach. The real power of 3D Construction Kit 2 lies with FCL- Freescape Programming Language. FCL is much like BASIC and gives a good degree of control over your blocky universe. If you want to create halfway decent games, however, you cannot escape from programming altogether.

The main editor has the same sort of feel as in the original 3D Construction Kit. There's been a redesign, but all the familiar icons and menus are still there.

There are new shapes, such as the flexicube - a cube with corners that can move independently - and the sphere, which looks like a circle from every angle. The Freescape Control Language has been rewritten with double the number of commands, giving much more control.

There's also a video-type function that enables you to take control of the player's movement. A welcome addition is a second disk with a library of 91 ready-made objects from mansions to the kitchen sink.

One thing that hasn't been improved is the speed, it's slower. The editor has also lost a lot of zip and the icons and menus can be unresponsive. It's not a huge step forward, so is it worth upgrading? Well, it really depends on how nutty you are about creating your own virtual world and how desperate you are for more functions. You pays your money, you takes your choice. If you are a registered member of the user group, then you can upgrade for £20.

Using 3D Construction Kit 2 can initially be a frustrating experience. There is lots to learn and some of it can be confusing. You need heaps of dedication and patience to get at the potential of this package. It can not make a Starglider 2, but with enough input from yourself, you can get an excellent 3D adventure out of it - and you never need go anywhere near the horrifying world of three dimensional maths. Yuk! For that alone it's an impressive piece of work.

The only real grumble is the speed. The editor is slow and moving around the virtual world doesn't merit a speeding ticket. An amazing package capable of pretty amazing things, virtually.