Llamas are llovely!
I replayed all of these games through emulation and Revenge was the only one that disappointed. The last 25 years have not been kind to Llamasofts most famous game but when I was a kid I loved it.
You play a camel (I assume a mutant one thats feeling vengeful) and whilst scrolling slowly from left to right you shoot down a variaty of crazy things. When telephone booths, alpine skiers and cigerettes come crashing into your furry hump you start to question the makers (the famous Jeff Minter) sanity.

Sheep In Space
Another Llamasoft game by Jeff Minter. You play a flying, lazer-shooting sheep... in space (try not to think about it to much). It was actually an excellent clone of Defender with the same free roaming and warping about. You had the novel ability to refuel by landing and eating grass which were dotted around. Failure to do so and you starved to death which is never a good way die.

Even the first level required some perfectly timed jumps
This is a platform game in its purist form. Just 3 buttons needed, left, right and jump. Created by the demi-god Mathew Smith (who also done Jet Set Willy), Manic Miner was a revolution in those early 8-bit computer days. The premise of each, single screen level was to simpley collect the flashing keys and make your way to the exit. Every level demanded that you learn the correct route, where to jump, how to avoid the crazy baddies and the evil spikes and death weeds. The slightest touch of any of these was instant death and with just 3 lives a steady hand and nerve was needed. Here's to games where you get chased by toilets!
I think Rockford meets a sticky end in the next frame
Not content with being a camel and a sheep Boulder Dash lets you play the role of Rockford the Ant (I swear it's purely coincidental). Your aim is to dig through the dirt collecting a set amount of diamonds and then finding the exit. The levels are littered with boulders which will fall on your head if you remove the earth from under them. Not only do you have to watch every step but there is the 'deadly shapes' (usually a square) that zoom around the passages you've just created. However this is where the boulder becomes your friend by pushing or dropping them on the 'deadly shapes' (this is a necessity on some levels as they explode into diamonds).

There was a few sequels and many homebrews and remakes through out the years including Boulder Dash Rocks on the DS and the PSP which are very much on my wish list.
Yie Ar Kung Fu
Yes there was actually fighting games before Street Fighter 2! I was quite the Yie Ar Kung Fu player. I'd knock seven shades out of all the characters with the grace one could whilst wearing white pyjamas. That is untill the dreaded Pole Guy. I don't know if it was a bug or not but if the Pole Guy snagged you with his lengthy green high jump pole he would continually hit you until you were dead. No getting away, no hitting back. DEAD! Your best bet of defeating Pole Guy was to jump around like a manic pyjama clad frog on a barbacue and get sly hits in.
That aside Yie Ar Kung Fu was a joy to play along with its colourful graphics and meaty sound effects. The sequel (imaginatively called Yie Ar Kung Fu 2) was just as good if not better.

Pole Guy... be affraid
