How do you name a video, in which you try one of existing game engines by making a "doodle" game in it. "Fiddling with XXX Engine" or "Tinkering with XXX Engine"?
"Tinkering" suggests working with something mechanical or technical, without necessarily having much of an objective--but still suggesting some amount of skill.
However you can be "fiddling" with something simple like a rubber band--bending it in different shapes while someone is talking. Fiddling can thus be somewhat equivalent to "fidgeting".
But in this context, they're nearly indistinguishable. It could perhaps be argued that "fiddling" suggests a lower level of technical involvement.
"Tinkering" is probably the better choice for being understood by people with various levels of English fluency (including automated translators), because it doesn't cross with the term "fiddle" as used to mean "violin".
Or is there a better choice?
Not enough context to know. If you don't want to sound completely unprofessional about it, you might say "A First Look at XXX Engine" or "Introduction to XXX Engine" and such choices might make it easier to find in searches. If you're deliberately wanting to sound casual you could say "Messin' with tha XXX Engine". Depends on the tone and style you want.