An aspiring barrister who used online gaming accounts to befriend children and incite them to commit sexual acts on camera has been jailed.
Owain Thomas, 29, of Pontypridd, used nine Facebook profiles and three gaming accounts, persuading some of his 146 victims with gaming credits.
He was arrested after he asked a group of young boys aged between seven and 14 to expose themselves at a playground.
He was jailed for 10 years at Merthyr Tydfil Crown Court on Friday.
Judge Richard Twomlow said he will serve an extra five years on extended licence and described him as "persistent" and "a significant risk to the public".
He pleaded guilty to what police described as an "unprecedented" 158 child sex charges at an earlier hearing.
The charges included causing or inciting children to engage in sexual activity, and watching sexual activity, possessing indecent photographs and distributing indecent photographs.
The court previously heard the Aberystwyth University law graduate used software to adopt the persona of children and pretended to be girls or boys as young as eight in order to incite others into sexual activity.
He created fake profiles on popular online games such as Roblox, an online multiplayer game, which has 90 million users worldwide and is marketed at children.
Thomas would then share footage he had recorded with other paedophiles.
He was finally caught after the young boys he targeted at a playground in a small town in Rhondda Cynon Taff told their parents, who then informed police.
After tracing him on CCTV, South Wales Police seized Thomas's laptops and devices from his home, and he told an officer: "That's the one I didn't want you to find".
Officers discovered 110 hours worth of abuse footage.
His victims - many of them aged under 13 and some as young as nine - were found to be from south Wales, west Yorkshire, south Yorkshire, Northern Ireland, Lancashire and the USA.
Sentencing Thomas, Judge Twomlow told him: "This may have been through a screen but this was a very real experience for your victims.
"You went as far as you could persuade these children to go. You had multiple identities including pretending to be a nine-year-old girl.
"An occurring theme in this case is your persistence. If you couldn't convince them, you would return and try again.
"Because of the sheer volume and scale of your offences I have no doubt that you are a significant risk to the public and pose a real risk. You are a dangerous offender."
Roblox was launched in 2006 and is a platform which allows users to create their own online games using a design tool.
According to the company's website, its most popular games have hundreds of thousands of players a day.
It claims that its popularity among users aged eight and upwards has "exploded", and that it is "now one of the top online entertainment platforms for kids and teens".
Players can comment on the games while playing them, and also chat with others.
Roblox said it "doesn't support video or voice chat, and it has extensive chat filters".
Det Insp Lianne Rees said many of the parents "had no idea" their children were even accessing some of the social media or gaming sites.
"A lot of the parents expressed quite a lot of guilt. Some even said they felt they failed as a parent to safeguard their child," she added.
NSPCC Cymru said the "appalling" case shows "once again the grave and increasing dangers that children face online and highlights the need for urgent action".