Evil Genius is that one 2HD, yes. It's so nearly a brilliant game, but not quite, IMO. The developers deserve massive kudos for the attempt and it's quirky, funny and wholly original. If there were an EG2 I'd buy it tomorrow.
But there NEEDS to be an EG2 to make it fulfill its potential, sadly. There are just too many things they got not quite right that will annoy over time.
If you can get it at a good price, though, it's worth getting.
