러 오다

'Come here to do X'

The purpose comes first and 오다 'come' follows, which makes it the standard way to say why you have shown up: 그래서 한우 홍보하러 왔어요! 'so I came to promote Hanwoo!', 오늘 뭐 사러 오셨어요? 'what have you come to buy today?' Learn 놀러 오다 as a set phrase — 오늘도 편하게 놀러 오세요 'do drop by and hang out today', which is an invitation, not a suggestion to play.