Qruton is actually called Numblast in the UK and was released on the UK PSP store 2 weeks ago for £3.99. I should know, I have it and I've enjoyed it a lot! I heartily recommend the demo. Some details below for you...
Storywise, you are Choco, a student who is experimenting with the Numblast cubes. Suddenly, there's a big accident and your teacher (who gets caught up in the blast) turns into a monkey. The only way to change him back is to align the Numblast cubes so they make the same number in a square (usually a 2x2 square).
So, at the start, you're given a board of numbers between 1 to 4. You can move any block of 4 clockwise or anticlockwise by pressing the x or o buttons (configurable in the full version). Once you've aligned a 2x2 or better square, the cubes turn red and count up by 1. If you combine the red squares to form another 2x2 or better square, or make a 2x2 square elsewhere, you can start a combo. The longer the combo, the better the points.
The cubes will start turning black during the level. You can't move a 2x2 block of black blocks but you can move black blocks individually or when grouped with one colour or blank block (left behind from a combo). If they all turn black, it's game over!
The full game has a puzzle mode, a time trial mode (3 minutes to get as many points as you can) and an endless mode with 3 difficulty levels.
This video will help explain everything. All clear? Go try it out!
Tutorial video and sample time trial
More information! The demo includes the 3 minute time trial (menu item 2) the manual (in Japanese :p) (menu item 4, then top option) and some tutorial videos (menu item 4, option 2). The unavailable options are Endless (menu item 1), Puzzle (menu item 3), options (menu item 5/6) and monsters (think Buzz! PSP trophies on menu item 5/6).
In Time trial, the left hand options are to play the game (top option) and to replay your saved attempts (bottom option).
After the trial is over (tip, if you start a combo before time is up, the game won't end until the combo ends!) you will see your score. After going through the obligatory BUY ME sign, you'll have options to retry, view your replay, save your replay to a file for later viewing (I don't believe this is saved after you quit though) and return to the menu.
The record screen will show your score, the number of cubes detonated, the highest combo you had, and the number of Numblasts (full screen explosions).
As a quick test, you try and beat:
Score - 581850
Cubes - 213
Combo - 17
Numblasts - 0
For a massive challenge, I dare you to beat my top score in the full game of 1,392,100 . Get blasting!