There aren’t many artists a lot like Mike Oldfield. The general genre of instrumental synth (including shadorne’s) suggestions) gets you the closest. Another suggestion is Larry Fast/Synergy. Some of Steve Hacket’s solo work. Some of Tangerine Dream. His sister Sally Oldfield put out a record "Water Bearer" similar in style, but a vocal record. Mike plays on it.
if you don’t have all of Mike Oldfields records, you may as well get them. My favorite by far is "Ommadawn". "Amarock" is great. "Music of the Spheres" and "Guitars" even better, and better still "Songs of Distant Earth".
