Some of the most successful apps are based on an idea so simple that at first, it hardly seems different enough to bother with. WhatsApp is just instant messaging, Snapchat is just disposable pictures, and so on, but that's also what makes them work - they're clear, well-executed ideas for doing a job just differently enough.
LokLok has that simple-but-brilliant feel to it. It's a lock screen that lets you take pictures and draw on them, and when you change your LokLok screen, the screens of the other people in your LokLok group change too.
READ MORE: the 25 Best Free Apps for Android
Fight your inner schoolboy
The first person I shared a LokLok screen with was Tom Parsons (Stuff reviews ed), and almost immediately I'd taken his picture and overlaid it with the sort of "artwork" found in maths books across the country. It's not big and it's not clever, but the satisfaction I got when he went to unlock his phone mid-meeting and did a double-take at the offensive image was simply marvellous. You can currently share your LokLok screen with up to five people, and the potential for mischief is huge.
You may not stay LokLok friends for long with those shenanigans, though, so I then tried putting it to its intended use - sharing nice little notes and pictures with my Significant Other.
The regularly changing screen, on which you can share notes and photos of things you've observed/eaten/visited during your day, is a very nice way of staying in touch. It's private, personal and more fun than just swapping texts or emails. And it can also be quite useful - while it's not much as a messaging app, it's pretty handy for leaving your other half a reminder to take the bins out. Unlike SnapChat, which very sensibly doesn't have an option to save pics, LokLok lets you keep any particularly memorable screens.
LokLok is currently in beta, so a few bugs are to be expected, but here's what needs fixing before it's a five-star app: it currently uses a fair bit of battery on some phones, and sometimes the LokLok screen just doesn't appear. Aside from that, it's a great idea that deserves to do well.