Ah, high-res graphics, the eternal question...
Ok, time to clear up some misconceptions. OpenXcom is not meant to be
just a complete reproduction of the original game. Sure, it just look like that
now, but priorities and all that. A lot of people think you can only have either the original experience or a new experience, but not both. That you can't have your cake and eat it. A lot of remakes seem to prove them right. Well, I choose to prove that wrong! I can have my cake and eat it too! It's just a really long-winded cake that takes years to make and the frosting is starting to melt and... anyways!
My ultimate goal with OpenXcom is to have a
fully-moddable open-source X-Com engine. This means that, by default, the game will always support the original gameplay with original graphics et all, no questions asked.
But, if that's not enough for the player, they can have more. They can mod the gameplay, the graphics, options, etc, however they want. It's up to them. OpenXcom will not try to enforce some "best" way to play, a lot of remakes have tried to do that and failed, in the end different people have different tastes and you just end up with a lot of bickering. Instead, it will be open as much as possible to whatever way they want to play. If that's not enough, they can even go all the way, take the code and adapt it into their own completely new remake. Maybe then they won't always have to start from scratch.
So, if that's the plan, why is the engine apparently so hardcoded to original gameplay and stuck on boring old graphics with routines only supporting old-fashioned pixel blitting and 8bpp palettes and so on? See, I don't have a problem with high-res graphics, really. Sure I love the original style, but I love fancy new stuff too, and I'd love it if my game looked like Xenonauts or XCOM: Enemy Unknown, and OpenXcom ran on this hardware-accelerated wiz-bang 24-bpp fancy-graphics super-cool-engine and it was the best thing ever and... but here's the catch, every decision a programmer makes comes at a cost.
So back when I first started, I had an option. I could have designed it from the start with this great big open architecture, supporting all kinds of mods, 24bpp graphics, open resolutions, OpenGL, etc. Or I could have just taken the easiest approach for getting the game running with what I had, original gameplay and graphics and all. In the end I picked the latter, since it was fairly experimental at the time, I'm a terrible artist and I'd rather work to my strengths. It kinda bit me in the long run because now the engine is fairly engrained in its 8bpp nature and it'll take one hell of an overhaul to fix that. But on the bright side there's an actual game with tons of gameplay to show for it, and if I had taken the former I might have this big open amazing perfect engine but with no actual content, so I remain confident.
Plus the retro look kinda helps keep it distinct from all the other remakes out there.
tl;dr: v1.0+