LÖVE

Following the shields idea, if I make shields consist of 3 color sliders, so you'd have to navigate along all 3 color components separately, rather than just hue slider, would this make up for a 6d game? No, obvioiusly. It's still a 3d game.

But I'm not finding that conclusion to be "obvious". Even if I did agree, it still leaves me with a contradiction - as sh'm'ups are, to me, equally obviously 2D, and I would not reduce them to 1D "with an extra degree of dodging" (which itself reduces to 0D "with an extra degree of dodging"), even though I am finding no distinction between a sh'm'up and our hypothetical colored-shields-game.

Play Adanaxis, and then play any true 4d game, and you'll see that former is just a 3d actually.