The UK Games Expo opens at Birmingham's NEC on Friday for its 20th show, with organisers expecting 45,000 visitors over three days. The tabletop gaming event, which runs through Sunday, has grown from a small gathering into what its founders now describe as one of the world's largest shows.

This year's expo will bring 900 exhibitors into six halls of the exhibition centre, a rise of 15% on last year, and will spread across more than 72,000 sq m of floor space at the NEC and the nearby Hilton hotel. The scale is a far cry from 2007, when the first UK Games Expo was held in a masonic hall and drew about 900 people.

Richard Denning, who helped launch the event with a church minister from Kidderminster and a retired GP from Sutton Coldfield, said it has outgrown anything they imagined at the start. He said, “We thought we could do something, but we never really thought on the scale that it's got to.”

Denning also said the expo has become “genuinely one of the world's largest shows and cements our position on that world stage,” while organisers say it is now the biggest event of its kind in the UK. The event covers board games, roleplaying games and miniature wargames, and also includes shows, seminars, re-enactors and cosplay.

For publishers, the show has become a major sales and marketing date. Roger Martin said it was “one of the most important dates in the calendar” and described it as a “rare opportunity to meet thousands of board game and trading card game fans face-to-face.” He said the event helps companies “engage new audiences and shine a bigger light on our titles, while giving existing fans early access to upcoming releases and plenty of hands-on play.”

Asmodee will have 10 stands and demonstrate 160 games at this year's expo, underlining how the event has become a commercial showcase as well as a fan gathering. Organisers say this year's turnover is projected at about £2.2m, another marker of how far the event has moved from its £18,000 first outing, which Denning said he helped fund with £5,000 borrowed from his wife and an inheritance from one of the founders.

The wider market has also helped fuel the growth. Denning said the UK tabletop games market was estimated at between £450m and £500m and was growing all the time. That backdrop, combined with the expo's reach, explains why Birmingham will host a weekend event that now fills the NEC and nearby hotel space rather than a single hall. The question this year is not whether the expo has arrived, but how much larger it can still become.