With Belle Shell set to capture the hardware keys on your old S60 5th Edition phone, you can appear to run much of the Symbian Belle front-end: swipeable homescreens, (some) widgets, swipe-down connectivity pane, flexible application menu, and so on. And it all really does work, as you'll see below.
Unfortunately, Belle Shell is no lean and mean application launcher. On its own, it takes up... wait for it.... around 25MB of RAM, around half of all free system RAM on many S60 5th Edition devices, which is clearly a major showstopper, in that with Belle Shell running your smartphone just got somewhat crippled. The sheer size of Belle Shell can also be seen in that it takes around 20 seconds to start up and load into RAM in the first place.
However, there's still plenty to see, even if (for you) it's just admiring the programming effort at a distance! This is Belle Shell in place on my 2009 Nokia X6:
An impressive result, right, very convincing - and fully working, everything drags and drops and swipes just as does the real thing on newer hardware!
On the left, the default starting homescreen; right, the reworked 4-wide application menu - why can't we have this on the real Belle OS, Nokia?
Left, everything is still fully working, complete with authentic menus; right, you need to tick the box so that pressing the phone's home key brings up Belle Shell and not your usual S60 5th Edition homescreen.
Only five widgets to choose from, though - the Belle illusion starting to break down; right, the drop down notifications pane is minimal, though it does have a handy LED 'flashilight' function - maybe Belle Shell is the world's largest flashlight utility?
As I say, with 25MB RAM needed for Belle Shell, it's completely impractical, but at least you now know what it does! Belle Shell is £1.50 in the Nokia Store here if you want a play too...