Hmmm, unfortunately I've only played Downwell. I can say Downwell is really great! But if you didn't get into either Isaac or Risk of Rain, I find it a hard game to recommend. It is cheap though, so I'd definitely recommend just buying it anyway and giving it a shot. It's a lot simpler that both Isaac and Risk of Rain like you said, so you might enjoy it. It's also on mobile platforms if that makes any difference.