Let's imagine you've discovered a list of intergalactic treasures represented by integers in an array arr. Now, you've got a peculiar rule out here in the cosmos: you can only pick up the treasures located at the even indexes in that array! Now, being a smart space explorer, you want to find out the net worth of all these even-indexed treasures.
So, here's your mission: craft a Python function recursiveSumEven that accepts your list-of-integers treasure array as a parameter and returns the sum of all those even-indexed treasures. And since this is the cosmos and peculiar rules rule, you'll need to calculate this sum recursively!
This function will be tested with different-sized lists, including ones with 0 elements, so do consider the edge cases! Sail high, space champion! Remember, the answer is always in the journey.