I’m porting dosemu to Haiku. Unfortunately this will have to wait until beta 6 (needs some missing features in beta 5, and also currently triggers a KDL in some cases).
It allows to run DOS apps almost natively, a bit similar to what Wine does for Windows. So here is Microsoft QBasic running in Haiku terminal 
There is also SDL support if you need to run things with a graphical display (it may be possible to write a GUI for it that doesn’t go through SDL and uses a native window, too).
On Linux this can use vm86 or KVM to run the DOS code on the native CPU. On Haiku we have no such things, but there is a CPU emulator in dosemu as well. Still, it will use host code running directly on Haiku as much as possible (to provide DOS and BIOS services).
It should even be possible to run Windows 3.1 in it.