You can either marry your girlfriend and go the marriage route.
Or as you say go the retirement route.
Having said that you never stated it was with a lady.
You are not eligible for a Visa on Arrival.
You are eligible for a Visa Exempt Entry.
You can then apply for the Non Imm visa and 12 month stay for reirement at Immigration.
You can only get a Non Imm O-A Visa in your country.