The paid alpha gamble paid off: Introversion's made more than $100,000 from Prison Architect.

The exact number as of this morning was $101,145. That's 72 hours after the game went on sale.

That represents 2667 sales, Mark Morris and Chris Delay revealed at the Eurogamer Expo this afternoon.

Prison Architect has a tiered pricing system inspired by Kickstarter. Prices range from $30 to $1000. And yes, people spent $1000.

Here's how those 2667 sales break down by tier:

Base ($30) - 1801

Aficionado ($35) - 343

Introversioner ($40) - 134

Name in the Game ($50) - 302

Physical Pleasures ($100) - 69

Digital-Immorto-Criminalise Your Face ($250) - 13

Shake it Like a Polaroid Picture ($500) - 1

Warden Norton I Presume? ($1000) - 4

Morris said he and Delay had been "absolutely stunned" by the reaction. "We feel like this approach that we've taken has been really successful," beamed Morris.

Chris Delay used his time on stage to demonstrate new features coming to Prison Architect in "probably" a month. One was default locked doors that guards will need to open. Sounds simple, but it changes a lot. Opening doors can take up a lot of a guard's time, and the repercussions can alter the entire design of your prison.

Another feature was tunnelling. It's not realistic, but films like Shawshank have made it prison lore. Your prisoners will pretend to be asleep but secretly be digging tunnels, and they'll try to shift dirt in the yard. They even collaborate and dig tunnels quicker together, the rogues.

Another feature is riots. If prisoners needs aren't met, they'll riot: huddle, hop up and down in rage and duff up any unfortunate guards. You can lose control of entire sectors of a prison to riots. And when you have no guard presence in a sector, a fog of war will creep in and gradually obscure the area. You'll have no idea what's going on in there.

Sectors gripped by riots turn red. Prisoners barricade doors. Guards won't obey your order to go in there. "It's above their pay grade," Delay quipped. "They're not going to go in there because they're going to get dead."

So you call the Riot Police, who are armoured, armed and tough. And you call some paramedics. And maybe a fire engine. Then you need to set about reclaiming the sectors of your prison.

Another feature Introversion is chewing over is gangs. Several iterations have been tried already, apparently. "But it just doesn't work yet," Delay said. He also mentioned contraband, but said it was another "very very difficult" mechanic to implement. Contraband could be thrown over walls or smuggled in through visitation rooms, then dished out via the laundry system. It's complicated.

Chris Delay demonstrated riots and tunnelling and locked doors and patrol routes during the session. The video of that will be uploaded probably next week. If you want a glimpse at the future of Prison Architect, watch it. Morris and Delay are also lovely and chatty, so it's entertaining as well.

Alternatively you can see the presentation for yourself at the Eurogamer Expo tomorrow at 3.30pm.

In summary, then: Introversion is happy, and the future's bright for Prison Architect.