If you have not heard of these games, then you have no idea what you are missing out on. Cryptark Megasphere Sublevel Zero I have been playing the hell out of Sublevel Zero. It is strongly reminiscent of Descent. It lacks inertia and gravity, but has an otherwise robust setup for weapons. I just bought Cryptark after watching someone play it for a while. It looks very challenging and is extremely enjoyable. It adds a new level of difficulty to an already great genre by making you have to decide how much of what types of equipment to take with you. Take less and you may screw yourself, but if you succeed you will make more money. Megasphere I do not own, but I have been watching carefully. It too looks great. I tend to hate platformers, but this one may be an exception since it looks similar to Metroid except with machines instead of Metroids.
Sublevel Zero reminds me of Descent and I could never get into it because I didn't like having no reference of position. So I likely will never get this one because of that. As for the other games, I hadn't heard of them but will keep an eye out and see what is happening in the future before I decide to buy or not.