The game came out of a recent Ludem Dare game jam themed around creating low-fidelity “de-makes” of games. Since 2002, Ludem Dare events have gathered programmers together for quick-and-dirty, weekend-long development sessions based on a community-chosen theme. Previous Ludem Dare entries have gone on to commercial release, such as the meta-RPG Evoland and the upcoming minimalist subway simulator, Mini Metro.
Purdy originally set out to re-create the game in 16×16 pixels, but found that the original’s map screens were built on a 16×10 tile grid, so with 4 pixels on top for UI, he managed to beat his goal by 32 pixels. Anyone familiar with the original will immediately recognize it through the minimalist graphics and know which walls to start bombing. He wrote an extensive, technically-specific blog post about the process on his personal website, which is an interesting read for anyone curious about how much work goes into even the most ostensibly simple games.
You can play the game itself here.