Here is How many wins it took to me to get level 20, yours might be around the same depending on your win rate. Ill post Murder Mystery as soon as it goes out!
Number of Games to get to level 20
123 Treasure wars (80% Win Rate)
89 Hide and Seek (59% Win Rate)
358 Death Run (87% Win Rate)
TIP : To calculate your win rate do [Games Played] ÷ [Games Won] ×  = Win Rate %
Fastest to Longest to get level 20
1 - Hide and Seek
2 - Treasure Wars (I played solo)
3 - Death Run (Even if I have a very high win rate, DeathRun = ~1:30 x 358 games which is a lot counting the waiting time)
If you want any other statistic, let me know or give me ideas!
Soon: Time to make the spawn Parkour