If by run-on sentence you mean a sentence consisting of two or more independent clauses that are not joined by a conjunction, there are run-on-sentences in German (the single subsentences have to be separated with a comma). A classical example would be the translation of Cesar’s “veni vidi vici”: “Ich kam, ich sah, ich siegte.” Whether your example is one, depends on as to whether you classify vor allem as a conjunction here. Either way, the example is correct but it could also be split into two sentences before vor allem, only changing the pace but not the meaning.
In either case there should be no comma after vor allem since it is no construction that requires or allows a comma (subordinate clause, extended infinitive, parenthesis, something being followed by a contrasting conjunction, …). This is in contrast to English where many adverbial constructions at the beginning of a sentence can or have to be separated with a comma.
If by run-on sentence you mean “a sentence in which two or more independent clauses are joined without an appropriate punctuation or conjunction”, then it’s a simple punctuation error (and not a grammatical phenomenon). An analogous punctuation error is possible in German, but rather rare, so we do not worry too much about it and do not have a specific term for it.