Whack-a-Mole: The CSS Edition

This article explores creating a Whack-a-Mole game using only CSS, a feat seemingly impossible given CSS's lack of built-in timers or interval functions. The key lies in leveraging CSS animations to manage game states and simulate timing.

The foundation is a pure-CSS double-click handler (detailed in a separate article linked within the original). This handler cleverly uses animation and element positioning to differentiate between single and double clicks. A double click triggers a specific action, while a single click triggers a different one. This mechanism is crucial for managing the game's interactions.

Two core principles are at play:

1. State Management via Animations: CSS animations are used to define and transition between game states.
2. Positional Control of Interactivity: Changing element positions determines which element responds to user clicks.

Instead of scrolling elements into view, animation-timing-function: step-end is employed to create the "pop-in" and "pop-out" effect of the moles. Positioning the mole using left (instead of transform) avoids layout issues in Firefox.

The "moles" and "holes" are styled CSS labels that interact with the checkbox hack, forming the game's interactive elements. When a mole is over a hole, clicking triggers the mole's radio input; otherwise, it triggers the hole's input.

Multiple holes and moles are implemented, each with unique animation delays, creating the game's dynamic mole movement. Python scripts were used to generate the CSS selectors and keyframes for the state machine, simplifying the otherwise complex hand-coding process. The "random" mole behavior is hardcoded due to CSS's lack of random number generation capabilities.

The result is a fully functional reaction-based game built entirely with HTML and CSS, showcasing the surprising capabilities of CSS animations for game development.

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