One of the best archive sites for retro games is Stairway To Hell (www.stairwaytohell.com) which is maintained by the same team as Retro Software. It features a near-complete library of every game ever released for the BBC Micro. Over the years, it has also found more than a few hitherto-unreleased ones too. Morfix, written by Andrew Stanford, is one of these and is a monochrome graphic adventure that I suspect few have seen - a shame, because it's rather unique in style.
You take control of a blob and your mission is to reach your girlfriend (another blob), situated in one of the many "rooms". You have only three controls - left, right and jump. When you want to pick up an item, you must move over it.
Scattered around the rooms are some shapes including a circle, square, star and figure eight. Movement of your blob involves rolling him, and contact with any of the shapes results in him morphing into that same shape (although his smiley face remains constant). You need to be a certain shape to get through the doors that correspond to that shape's outline. Mission one therefore is to make a map - so you can see, at a glance, what shape you need to be in which room. Otherwise, you'll waste lots of time trying to remember where each particular shape is located.
Mission two concerns the other items you will find. Smaller items can be picked up and carried. Larger items are those which require you to hold a corresponding smaller item. When you do, they increase the "percentage complete" in the top centre of the screen and allow you to make further progress. For example, taking the coin to the balloon machine will operate it. When it then releases a balloon you can climb on top of that balloon to reach a higher platform and a new room.
Finally, mission three is the obvious avoidance of the patrolling monsters that live in each room and are anxious to deplete one of your five lives. Morfix isn't particularly big and the solutions to its problems aren't particularly difficult. However, though I did manage to complete it on my eighth go, it did require thought, planning and a fair dose of arcade skill. That certainly deserves a recommendation when it is completely free of charge. It can be downloaded from Stairway To Hell and seen in action here.