...play through portal again. Not the challenges or any downloaded maps. Just play through the main story and see what the main appeal is.

The reason I say this is that every portal map or mod that I have downloaded has focused on the skill involved in using a portal gun. Playing through Portal for the first time, I was never stuck on a puzzle for more than 15-20 minutes and even that was only on one or two of the later puzzles. Thats not to say that I was ever particularly talented. It was merely a matter of design. Valve managed to perfectly balance the difficulty curve so that every technique was demonstrated and tested before it was ever incorporated into a puzzle.

Of the downloaded maps, one level managed to stump me before I even left the opening room. I was stuck in a tiny cell with a bed, radio, clipboard and cup, the same as every other Portal mod and Portal itself. Only this time, I couldn't figure out how to escape it. I don't expect the level of polish and attention to detail that Valve produce but surely this should be something that's avoidable.

Two of the biggest mods for Portal are Portal: Prelude and Portal: The Flash Map Pack. I recently finished both of these. By finished I don't mean "Played through to its finsh", I mean "Played until I got stuck and now I'm finished with it". In Prelude, I got stuck in Test Chamber 2. At the very start, theres a gap that's too big to jump over. I thought I had a solution for it but i always fell just slightly short. Eventually I gave up and looked at the official walkthrough video. It turned out that I had the wrong solution. I loaded up Portal: Prelude again thinking that I could easily pass the puzzle now that I had the solution. However, I didn't have the precision jumping and portal aiming required and even after watching the video another few times and attempting again, I still couldn't make the jump. Since this, I haven't loaded up Prelude.

This was particularly disappointing as until then Prelude had been making a very good attempt at what was actually the main appeal of Portal for me and for a large proportion of other Portal players: narrative. Portal managed to tell a great story with a great character in Glados and even managed to turn an inanimate object into an internet sensation. For any Portal mod to capture the spirit of Portal, they have to focus on what made Portal great. Not on precision jumping. Not on tricky techniques. Not on tough puzzles. Instead focus on the story, the narrative, the characterisation and the feel of the environments.

Obviously, anyone making a mod wants something that sets their mod apart from other mods and from the game its based on. But making a mod that only 10% of people who own the original game can play is not the way to do it. Here's an idea I'm throwing out there for free. Taking a nod from Braid, what if you had a set of puzzles, some of which can't be solved straight away. Instead of the game being a set of linear test chambers, it could be arranged more like a pyramid with puzzles all around and completed in layers. To get to layer 2, all the puzzles on layer 1 have to be finished. This would allow tougher puzzles that the player walks past and can look at and solve if they're already that good. Otherwise, the player perhaps attempts the puzzle and when they can't finish it, they move onto the next puzzle. This way, you could let players who know how to use advanced techniques advance without boring tutorials that can be placed after the puzzle at some stage for less advanced players (like me) to be taught the techniques step-by-step.

Of course, none of that addresses the need for narrative based gameplay. That is something that will most likely change from mod to mod but in a game like Portal is essential. Even if you don't manage the heights of Glados it is imperative that any Portal mod at least attempts to include some form of story.