Seems entirely appropriate in this case.

I don't think that's accurate. There's not really any notion of "success", and the most important part of the process is that changes are made effectively at random and either propel the species forward by some minor increment or never make it past being rare curiosities.

Wait...

I don't think unguided is an appropriate descriptor for an evolutionary process (by definition or in the scope of PHP's history). However, your point about success is right on, and seems to fit the 'evolution' title and the language.

In natural languages, words have multiple meanings. You may want to actually choose one that fits the case, not one that represents it in most perverted and unfavorable light. Just sayin'.

>unguided

I wouldn't say so. Most species (read: groups, not individuals) adapt when nature throws an exception they can't handle. Mutations capable of handling these exceptions become predominant in a group, while obsolete gene pools die off.

PHP shows too little of this for its progression over time to be called "evolution."