I have mixed feelings about retro style games that are mere copycats from the golden age of video games. I get the nostalgia aspect, but the odd reality is that I cherish the memory of playing those old school games more than I actually enjoy playing them today. When I do play them, it's an immediate reminder of where games are today and how far along games have come and why products have advanced the way they have. While old school games were considered technically superior in their time, they are considered technically inferior today. In fact, most games of yesteryear made the most of the technology available to them. So designing a technically inferior product today, on purpose, is not that impressive to me.
Many great old school games are classified as abandonware and the ROMs and emulation software can be easily found to play them for whatever gaming system you cherished the most. Find them, play them, and try to enjoy them the same way you did 30 years ago. I've tried, but it's not the same. Reflecting on the memories of playing them gives me more pleasure.
Oniken is a good copycat from an era gone by, nothing more, nothing less.