A midfield-dominated first-half saw the visitors take the lead through a Gerald Arkson curler in the additional minutes of the first half.
It was the home side who went very close to breaking the deadlock as Wa All Stars goalkeeper, Fatau Dauda was called into action after an attempted lob from a distance in the 19th minute.
That effort from the edge of the box saw Wa All Stars end the half with a 1-0 advantage.
Hearts of Oak had to wait until the 77th minute to draw level through Obeng who headed in a cross from Sumaila Ibrahim.
The game went on to finish 1-1 as both premier league sides shared spoils at the Accra Sports Stadium.