приходил - прошеднее время пришел - настоящее время ко мне кто-нибудь приходил (вчера/на прошлой неделе/ в прошлом месяце)? ко мне кто-нибудь пришел? (уже, сейчас)

1) The difference is the tense. Пришел - somebody came and still there, waiting in the guest-room. Приходил - somebody came and already left. He's probably not here anymore. Synonim - заходил. Ex. that I can think of: - Ко мне никто не приходил/заходил? (Did anyone ask/visit me?) - Да, был Саша. Сказал, что зайдет попозже. (Yes, Alex was (has been) here. He said, that he would come later.) - Ко мне никто не приходил/заходил? (Did anyone ask/visit me?) - Саша пришел. Ждет тебя в гостиной. (Yes, Alex came. He is waiting for you in the guest-room.) As well: - Ко мне никто не приходил/заходил? (Did anyone ask/visit me?) - Был Саша. Пришел, выпил чаю, и убежал по делам. Сказал, что зайдет попозже. (Yes, Alex was (has been) here. He came, got some tea, and ran away. He said, that he would come later.) 2) Приходил - continious in the past or series of repeated actions (visits) in the past Пришел - used when you talk about 1 or several events, state the fact, the event that already happend, final state. Обычно он приходил раньше всех. Пару раз он пришел раньше других. Мы ждали его 2 часа, а он все не приходил. We were waiting for 2h, but he was not coming. Two actions lasting in the past with out final state. The reader should expect some outcome to close the case. Мы ждали его 2 часа, а он так и не пришел. We were waiting for 2h, but he didn't came. The case is closed.

Right, logically the word which should be used there is "пришёл" but for some reason we would rather use "приходил" there. Why? The answer is just because. That has got nothing to do with grammar, we just say it that way and this is it.

Vasya, отличный ответ)))

Understood, thank you Vasya!