Ask HN: Flash game devs, why don't you cover other people's games?

So, I was wasting my time yesterday and stumbled upon this little Flash game: http://adamatomic.com/canabalt/ . The author says it was made in just five days, but it's extremely well-balanced and hits the right emotion perfectly. This got me thinking: why don't Flash game developers make cover versions of other people's games that they adore, like musicians do with songs? Faithfully reproducing a good piece of work, capturing all the little details and maybe fixing the little shortcomings, sounds like the perfect workout for technical skills involved in game development.

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For example, here's a short list of minor details about Canabalt that I'd fix if I were making a cover:

- When the character hits the void below a crane, it shouldn't stop him like a wall.

- When the character hits a crumbling building and falls, the building should continue crumbling instead of freeze.

- The jump button should be a little less twitchy, because right now it's too hard to reliably make the smallest possible jump.

- The randomly generated map shouldn't include jumps into windows below the current roof level, because judging from Internet comments, this rare situation reliably kills most players regardless of experience.

- The music shouldn't contain those long lulls every now and then.

- Remove the falling rocks from the bomb death animation, they look lousy.

Note that none of those are new features per se. New features are things that require creativity, and they sound more like this:

- Add a speed indicator.

- Replace bombs with hostile robots digging from below or falling from above, with identical mechanics.

- Add the option of jumping into a friendly gunship and escaping at the 5km, 10km, 15km marks etc.