I gave the player a panic button

A tower-defense player spends most of the wave doing nothing. You place your towers in the quiet, press go, and then you watch — cheering or wincing, but not acting. The board plays itself. That gap always bugged me: the tensest moment of the game has no verb attached to it.

So I gave the player a hotbar.

A stockpile, not an upgrade tree

Three slots along the bottom of the screen, each holding one consumable — a one-shot power you fire mid-wave. The economy is deliberately un-clever: you buy consumables with Data (the meta-currency) in whatever quantity you like, they pile up in a stockpile, and each use spends one forever. Separately you buy the slots — you start with none and work up to three — then assign one consumable per slot. Fire one and that slot goes on a shaded radial cooldown before it’ll fire again. Stock limits how many times you can; the cooldown limits how often.

The first three are instant and board-wide. Coolant Dump flushes every tower’s heat at once — the panic button for a board that’s redlining. Viral Push dumps a slug of satisfaction onto the whole funnel, tipping the almost-converted over the edge. Rate Limit throttles every user to a crawl for five seconds — a breather when the lane’s about to break.

The best consumable is a wall

Instants are fine, but the one I actually wanted was a thing you place. And in a game about shipping an AI product, the most natural wall in the world isn’t concrete — it’s compliance. So the placeable consumable is red tape you drop straight onto the path, and users jam up behind it.

One gate wasn’t enough, so I split it into three escalating tiers, each pricier and longer-holding than the last: Cookie Consent (a quick 5-second stall), GDPR (10), and the AI Act (a full 15-second conformity review). You drop one using the same tile-highlight system as placing a tower, the line backs up, and your guns keep serving the stalled crowd — a manufactured kill-zone, on demand.

(My favourite detail: I’d just added a Regulator enemy who fines you and audits your towers as he walks. He strolls straight through your compliance gates. He’s the one who enforces them.)

Then I shipped it and felt nothing

Here’s the turn. All of that worked — and it was completely flat. Every consumable fired the same generic expanding ring. The three gates were three identical translucent rectangles that differed only in colour. Rate Limit was the worst offender: it genuinely slowed the entire board for five seconds and you could not tell it had happened. A mechanic you can’t see isn’t a mechanic — it’s a number changing in the dark.

So I spent a day on legibility, and it handed me the rule I should have started with: the effect has to read as the thing it does.

Rate Limit now tints every user violet and drops a scanline wash over the board — the throttle you feel is finally the throttle you see.

Coolant became a wave of frost sweeping outward, each tower coughing an ice-shard burst as its heat bar empties. Viral now cascades down the funnel in path order instead of blinking everywhere at once, so you watch the hype spread. And the gates stopped being rectangles: Cookie is a browser consent banner with a blinking “Accept all,” GDPR is a form that ticks its own checkboxes as the timer runs down, and the AI Act is a striped review barrier with a paperwork bar creeping to full. Each one slams down with a rubber-stamp thunk and dissolves upward when it lifts.

What it changed

The mechanic took an afternoon; making it feel like a mechanic took longer — and that’s the part worth keeping. The hotbar turned the wave from “did I build enough” into “do I spend my panic button now, or gamble on ten more seconds.” The player finally has something to do at the moment it matters. And every one of those somethings now announces itself loudly enough that you know, instantly, what you just did.