Seoul-based "free-to-play" computer game titan Nexon on Wednesday blasted into the US videogame arena with a "Combat Arms" online first-person shooter title that makes its cash from optional "micro-transactions" by players.

"Combat Arms had a great beta run, with players of all levels loving the fast-action FPS game play and in-game community features for ranking and challenging other players," said Nexon America spokesman Min Kim.

The game makes its money from players that buy animated helmets, outfits, emblems or other virtual items to customize in-game characters.

To keep the battlefield even, players earn experience or advanced weaponry by skill so people essentially can't pay for power.

"People can't buy uberguns to get a tremendous advantage," Kim said while demonstrating the game for AFP in San Francisco earlier this year.

US videogame powerhouse Electronic Arts (EA) has started investing in free play and is putting the finishing touches on a "Battlefield Heroes" war game supported by in-game transactions instead of up-front purchase prices.

"We expect it to be the world's largest PC (personal computer) action game," 'Battlefield Heroes' franchise executive producer Ben Cousins said while showing AFP the game recently at EA's offices in Northern California.

"It's a Web project as much as it is a game project. It's what you love and are addicted to about Facebook and what you love and are addicted to from 'Battlefield' smashed together."