C64 - The C64 version has by far the lowest detail, as is evident from these screenshots, there is next to no ground textures and not as much detail in the level backgrounds, the C64 version seems to go for a much more realistic style to it's graphics in comparison the the other 8-bit conversions

Spectrum - Highly detailed, great floor textures and backgrounds, stylised cartoony graphics

Amstrad - The Amstrad version looks to be a direct port of the Spectrum version, and therefore has an almost identical level of detail, there seems to have been a change made to the main character sprite as he is now thinner than before, causing his right arm to look a little out of proportion

C64 - Good all around use of colour, the C64 Pallet seems to fit the gritty style of the game quite nicely

Spectrum - Colours are garish and used quite sparringly, colour clash problems are evident, though the programmers have been very careful not to let it affect gameplay, bullets are big, colourful and easy to see

Amstrad - A pallet swap of the Spectrum version but similarly garish, there are also less colours on screen as the programmers were using the Amstrad's Mode 1 graphics which has a limitation of 4 colours on screen at any given time

C64 - Fast, smooth Animation with lots of frames, first rate job

Spectrum - Pretty good, nowhere near the level of the C64 version but the character still looks pretty good in motion

Amstrad - not bad, doesn't seem to be as well animated as the Spectrum version though for some reason

C64 - very nice smooth scrolling, pretty much faultless in this area

Spectrum - The scrolling is, unfortunately one of the worst things about the Spectrum version, it is quite jerky and the screen is "pushed" forward, instead of moving with the character

Amstrad - Pretty much the same as the Spectrum

C64 - nice arangements from the original arcade version, some of them can start to grate after a while but the general quality is what people had come to expect from the Commodore's fantastic sid chip

Spectrum - very impressive, some of the best music ever to appear in any Spectrum game, can even hold it's own easily against the C64 version's music, the music is also dinamic, changing whenever you run into a boss

Amstrad - no in game music at all, the title screen music is pretty good though

C64 - Really good sound effects, everything sounds as it should

Amstrad - not too bad, not quite as good as the C64's but it still does the job rather nicely

Spectrum - Pretty awful really, gunfire sounds more "squelchy" than anything else, nothing really sounds like it should

C64 - Missing the car at the beggining of the game, as well as a cut-scene towards the end of the game

Spectrum - includes the car, and also a cutscene where the Commisar threatens your family

Amstrad - the same as Spectrum

Controls - The C64 version controls slightly differently to the others, mainly due to the fact that you have to buy the rapid fire power-up to be able to hold the fire button down, in other versions you can do this from the get-go, allowing you to always be able to hold the fire button and aim up without accidently jumping, this causes you to have more control over your character

Weapons - The C64 version randomly allocates the weapons available to buy, other versions always have the same for each specific level, The Amstrad version has fewer weapons choices than the Spectrum version (no shower)

The Amstrad version is still very good, but it is basically just a watered down version of the Spectrum game, it's missing some of the best aspects of the Spectrum version (such as it's excellent music and the shower power-up) but has very little in it to give it anything over the Spectrum version (the only things I can think of are, no clash, and better Sound FX, there are also some nice pallet swaps for some of the stages), which makes it hard to recommend, the gameplay is still however there in spades, which is the important thing anyway.

It's actually a very difficult decision to choose between the Commodore and Spectrum versions though, the Spectrum version is more original, playing more like a precursor to the Metal Slug series, whereas the Commodore version tries to be as accurate to the arcade version as possible (making it very much a Contra derivative, just as the original arcade was) the biggest problem with the Spectrum version has to be it's iffy scrolling, which looks pretty nasty until you get used to it, whilst it's strengths are definately it's massive weapon power-ups and big chunky bosses (I feel that the final boss is a bit of an anti-climatic let down for the C64 version in comparison to the Spectrum's, to me, it just looks more like the disembodied head of a poor senile old man who doesn't know whats going on anymore than the intimidating final boss it's supposed to be)

I'm going to go with the Spectrum version, at the end of the day, it's more its own game and I feel that it has the slight edge over the Commodore version gameplay wise, it's so close though that it could have easily gone either way to be honest, so I wouldn't be surprised if people would disagree with the result, but I am pretty sure i've made the correct decision