Parasail was heading to a tech expo and wanted people to stop at the stand. It's hard to grab attention with sides, and easier with a game. So together with Ish Studio I built Parasail Defense: Space Invaders, but the invaders are LAG, CAP, GPU and OOM, and you are the inference cloud holding the line.

One rule

The whole game is one extra decision on top of Space Invaders. Token pills drift down between the problems. Catch them and you score. Shoot them and it's wasted compute. The same button that scores is the button that costs you.

That's the pitch for the product too, which is why it works on a booth.

Grey boxes first

The first playable version had no brand at all. Flat shapes, two colours. I wanted people to judge how it felt, not how it looked. The branded pixel art skin only went on once the mechanics were locked.

What playtesting found

This was the fun part. Things I would never have caught alone:

The pills were luck. I measured 47 of them and 25 could not be reached from the far side of the screen. One spawned below the ship. Now every pill takes 3.2 seconds to land wherever it starts. Measured again: 0 of 47.

Standing still gave you 100% accuracy. Fire nothing, miss nothing. And accuracy was a third of the score. Oops.

Nobody understood "uptime". It was ten lives wearing an SLA label. Now it's ten pips. Kept the word though, it carries the pitch.

You die holding the trigger. And the trigger was also "play again". So rounds ended and restarted in the same breath, score unread. The score screen now locks for a moment first.

"I need one second more." So problems now shake and tick for a second before they dive. Shoot them during the wind-up and the dive is cancelled.

Built for a booth

• Controllers first. Nothing needs a keyboard once a pad is plugged in
• One, two player co-op, or versus
• A callsign is required to play, so every player is a lead
• A scoreboard that resets each day
• Sound is synthesised in code, no audio files
• The whole thing builds to a single 146 KB HTML file. Email it, put it on a USB stick, double-click, play

No framework, no dependencies, no build step for the dev version.

Built with the team at Ish Studio.

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