Portal for DS
Portal Flash Version on newgrounds looks better.
This has too much background crap. Not Aperature at all.
2d portal = dead boring
it might be just as challenging but seriously without the 3D element portals is worthless.
This post has been edited for the safety of the lulz. --Duffedwaffe
I love my psp, and have done ever since I discovered the wonders of custom firmware and homebrew.
I can't get homebrew to work, cos my psp is on firmware 3.90, and there's no downgrading software for it yet. And it's an old fat one, which makes things even more difficult.
You can still install custom firmware using a pandora battery (google it), which is a combination of a softmodded battery and a specially prepared memory stick.
It helps if you have temporary access to a psp which already has custom firmware installed, as this psp can be used to create the memory card, and softmod the battery.
If you don't know anyone with a modded psp, you can also buy the battery/memstick combo on ebay.
This method works with all psp models to date, and can also be used to "unbrick" psp consoles that have corrupted firmware.
It helps if you have temporary access to a psp which already has custom firmware installed, as this psp can be used to create the memory card, and softmod the battery.
If you don't know anyone with a modded psp, you can also buy the battery/memstick combo on ebay.
This method works with all psp models to date, and can also be used to "unbrick" psp consoles that have corrupted firmware.
Jesus that's a lot of work for nothing.
Actually, the whole process takes about 5/10 minutes.
Also, I don't get what you mean by nothing. There are plenty of benefits to having custom firmware. It makes the PSP far more useful.
Things you can do are:
Backup your games as ISOs to the memory stick or PC, and play them without ever needing disks again.
Control your PC wirelessly via VNC.
Run a wireless FTP/HTTP server
Scan for, and connect to public (or unsecured) wireless networks. (ie: free internet all over the place 
)
Stream video content to the PSP wirelessly from your PC, in excellent quality.
Convert and play your entire back collection of Playstation 1 games.
Use your PSP as a universal remote (fat psp only)
Use many working emulators for most older computers and consoles.
Run a large amount of homebrew applications of various kinds.
And the list goes on. These are just a few of the benefits of a cfw PSP.
Also, if piracy was your thing, you could in theory play every psp/ps1 game for free with custom firmware. I don't encourage this, but the option is there if people choose to use it.
I can understand if you can't see the appeal in it, but as the saying goes, one man's trash is another man's treasure. Personally, I think it's excellent. 
Thanks Nocturnal, a lot of good help there. And it appears I have once again killed the topic on a thread. *updates killboard*
I'll attempt to get the thread back on track:
I just downloaded and played this game, and I must admit, it's not all that bad for an early effort. I had some initial problems launching it on (an m3 slot 1 card), but i found a comment that said it could be loaded via another app (DS organise), after which it worked fine.
The game is basic, and the levels look nothing like Aperture, but it's not too bad. The puzzles are fun, and make you think for a second, there are a few GLaDOS voice quotes that add to the atmosphere, although they are rather random.
So far, I have played 16 levels, and have seen many Portal elements (crates, energy ball launchers, turrets etc.). The control method is somewhat awkward, but once you get to grips with it, it's bearable.
All in all, not too shabby for an early version.
Of course, a PSP version in full 3D would be miles better 