I suppose it deserves some credit for being a vastly different experience from anything else on the NES library at the time, but every good idea here has its execution at least somewhat botched. The stealth element is hamstrung by inconsistent/buggy line-of-sight mechanics and an abundance of cramped spaces. The action element is ruined by the wonky perspective that ensures you will very frequently get stuck on corners trying to evade enemies or avoid falling into pits. And the non-linear explorative aspect (which I think had the most potential) was turned into a complete chore by the awful inventory system.

I was quite intrigued by how many tropes and gameplay beats from here made it into the Metal Gear Solid series (the tank boss fight and the electrified floors being two examples), but unlike say early Street Fighter or early Dragon Quest games in which there is still a lot of stuff to like, this just made me wish I was playing Metal Gear Solid instead.

Disclaimer: I've been made aware that the NES version is a port of the far better MSX game, and I do intend to experience the original at some point.