The most fascinating DS game? We've found it. And it's free

Here we are again at our weekly stroll through the sometimes confusing world of homebrew software. Each week we prove that pretty much anyone could (and should) dip their toe in the homebrew waters.

As you may remember, I'm abstaining from any commercial games or software on my two portable machines. So far the homebrew community has done me proud, this week being no exception. (In fact as you'll read, one particular game has even got me to reconsider a PlayStation 3 title that until now had remained under my radar.)

The pick of the crop this week (by quite some way) is Pocket Physics on the DS. This ingenious piece of homebrew enables you to create fully interactive worlds on the little handheld.

Simply place a number of static or free-moving shapes, pin them together in the shape of anything from a skateboard to a car and click play to watch the action unfold. As with the PC game Crayon Physics, the various objects then interact as they would in the real world. Things fall over, roll down slopes and swing from hooks.

It is absolutely fascinating.

Those of you who stray from the cloister shores of pocket gaming may see a similarity with the upcoming Little Big Planet on PS3. This is with good reason because Pocket Physics (even with its limited implementation) delivers an experience that draws from the same pool of fun. In fact, I hadn't really been looking forward to Little Big Planet, but having spent some time with Pocket Physics I'm now sold on the idea. If only Sony could deliver this experience on PSP, we'd be set!

Talking of PSP, although the majority of my time this week was taken up creating physical worlds and then knocking them down, I did get to dabble with a nice bit of PSP homebrew. I managed to while away my commute to and from work with PSP Filer.

• For Firmware 1.0 just copy the Filer folder into PSP/GAME.
• For Firmware 1.5 split the Filer folder with ExportPBP and copy into PSP/GAME.
• For Firmware 3.xx, copy the Kernel3 folder into PSP/GAME.
This piece of kit is a bit like Windows Explorer, only for your PSP. During the long train journey into the big smoke, I happily tinkered and cleaned the contents of my Memory Stick Duo. A bit like shoving my hand down the back of our old sofa, I was amazed what ageing rubbish I had been carrying around with me.

This release has the added bonus of being able to open RAR archives, so no nook or cranny was safe from my (slightly premature) spring cleaning.

Quite a productive week, all told. I now have a clean PSP Memory Stick and a whole collection of different physics experiments to show off my game design skills. Don't worry, though: I'll be back next week with more trivial homebrew to enjoy wasting your time on.