A minor detail: do any of the "time" variables cross midnight? If you have a starttime of 23:59 and playtime values like 00:10 you have to deal with possible negative time interval values for comparisons of start of win streak.
I'm not quite sure how your problem would work if the same player had multiple starttime values, play sessions in effect.
For consideration, when you have a two value variable, such as your Result, you may want to consider using a numeric 1/0 value as there a many things that can be done with such much easier than with character values. For example if you code 1 as win and 0 as lose then the SUM of the result over any group of observations is the number of wins, the Mean would be the percent of wins in decimal form, i.e. .60 = 60% wins.
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