A 19-year-old New Zealander has died of a "serious head injury" after playing a tackling game, believed to have been inspired by a controversial new high-impact collision sport trending on social media.

ALARM BELL

Although the game has long been popular in New Zealand, concerned citizens say the death is a reminder of importance of safety measures.

GONE SO SOON

= The youngster, identified as Ryan Satterthwaite, died in hospital after a game of "Run It Straight".

- The game has two players -- one with a ball, the other the tackler -- who try to knock the other one down.

ONLINE TRACTION

- The tackle game, where participants compete in full-contact collisions without protective gear, has been gaining traction on social media, clocking up tens of millions of views.

- In some videos, participants are seen passing out after being hit.

- At the game where the tragedy happened, over 1000 people turned up to watch eight men compete for $20,000 prize money.

- Some participants were injured during their matches, and one video showed a man having a seizure after colliding with his rival.