Add 4DO, NXEngine, and Virtual X86000

Core-Requests.md

@@ -2,6 +2,10 @@ This page documents various emulator core candidates and specific user requests
 
 TODO merge in [Yoshi's list on GitLab](https://gitlab.com/TASVideos/BizHawk/-/snippets/1890492)
 
+## (3DO) 4DO
+- https://sourceforge.net/p/fourdo/code/HEAD/tree/trunk http://fourdo.com
+- C# (net40); GPLv2
+
 ## (3DS) Citra
 - https://github.com/citra-emu/citra https://citra-emu.org
 - C++; GPLv2+
@@ -25,6 +29,10 @@ Tracking as [#1907](https://github.com/TASEmulators/BizHawk/issues/1907).
 ## (BBC Micro) beebjit or BeebEm or B-Em
 Tracking as [#2031](https://github.com/TASEmulators/BizHawk/issues/2031).
 
+## (Cave Story engine) NXEngine
+- https://nxengine.sourceforge.io (source distributed as archives)
+- C++; GPLv3
+
 ## (Coleco Adam) MAME subset
 - can likely copy most Hawk-side code from MAME Arcade core
 
@@ -67,4 +75,10 @@ Tracking as [#3318](https://github.com/TASEmulators/BizHawk/issues/3318).
 	- Has a software rendering option which is fast enough; should probably go with that even if not Waterboxing.
 	- There has been some success with running PPSSPP standalone in libTAS, see [this forum thread](https://tasvideos.org/Forum/Topics/20542).
 - Other emulators:
-	- [cspspemu](https://github.com/cspspemu/cspspemu) in C#, unfortunately targets .NET Core
+	- [cspspemu](https://github.com/cspspemu/cspspemu) in C#, unfortunately targets .NET Core
+
+## (X68000) Virtual X86000
+- https://bitbucket.org/kazssym/libvm68k/src https://www.vx68k.org/vx68k
+- C++; GPLv3+
+- Other emulators:
+	- [PX68K](https://github.com/hissorii/px68k) (in Japanese) in C/C++; no license, though the author granted RetroArch distribution rights