Your output is not correct.

Lua test is not working correctly

I had a similiar solution. There's a few things you can do to shorten the code up a bit though.
You don't need to range through the list if you are trying to iterate through the elements. Simply, 'for word in words' will get you each element in the list.
instead of getting the len() of the list you can use indexing to check the last element; 'words[-1] == (len(words) -1)'

Just keep trying to simplify your goal. Be as general as possible. What data type should every element of the string be?

Glad to see I wasn't the only one to error handle int()

It's a snake

You can reduce even more by only using two 'ifs'
Index 1, if it's 'e' then it is not green

Cool I came to the same solution but wrote out three to show readability