someone already mentioned this same thing for "dead silence pro"
but these "tricks" are just easy challenges that alot of people arent aware of.
so what you do:
get marathon pro. (this is the only time consuming part)
then theres a challenge called "parkour"
all you need to do is climb up and down objects. cars/trash cans.
you get alot of xp though
the challenges are 1000xp, then 2500 xp, then 5000 xp, then 10000 xp. plus you get an emblem

this can all be done in 1 game if youre near a trash can xD