You have not given us a sentence containing the words "long time ago". Please write out the entire sentence twice - once with the past simple and once with the present perfect. Remember to put a full stop at the end of each sentence.
Thank you for providing the full sentences. As you can see above, the first doesn't work but the second does. However, note that it's not impossible to use the present perfect with the phrase within one statement. For example, you can say "I have played this game once - a long time ago".
Note that the correct phrase is "a long time ago".