Learn Russian: Ему повезло: билеты ещё были.

The verb повезти (to be lucky) requires an impersonal construction. Instead of saying 'he was lucky', Russian literally expresses 'it was lucky to him'. The person experiencing the luck is placed in the Dative case (ему), and the verb takes the impersonal neuter singular form (повезло). This strictly matches the Dative experiencer pattern you are currently learning with state words like лень and пора.

Is повезло perfective or imperfective, and why does it matter here?

It is perfective. It refers to a single, successful stroke of luck with a clear result: he managed to get the tickets this specific time. If the sentence used the imperfective везло, it would mean he was generally or continuously lucky over a longer period, rather than just in this one specific instance.

Why use a colon instead of a comma before билеты?

In Russian punctuation, a colon is often used between two independent clauses when the second clause explains or provides the exact reason for the first one. The fact that the tickets were still there is the direct explanation for his luck. You can mentally replace this colon with потому что (because).

Can ещё mean 'more' in this sentence, as in 'there were more tickets'?