Its been a while since I last posted around these places. I'm building a 3D engine from scratch using only SDL and since I had a gameport compatible joystick I thought it would be awesome to port it over to Windows 98 and run some performance tests as well on my K6-2 PC.

Do you folk know if the Microsoft Compiler from VS2013 can output Win98-compatible code? Or what options would I have to compile for this platform? I'm fairly sure my dependencies are compatible and my code is C98 compatible.

No. You need MSVS 6.0 for true compatibility. If you don't mind depending on .NET, then you can go as far as MSVS 2005. But no further. Win 9x/ME went EoS on Jul 11, 2006. MSVS 2008 already requires patching to work, when it does work. Later versions rarely do work, even after patching. And, BTW, MSVS 2013 is tricky to get working already on XP SP3 !!! So, no, it cannot. Sorry.  

 Hm... I was afraid it might not be possible . Alas, I could create a VS2005 solution and just keep both codebases in sync. Sure, it's going to be a bit of a pain having to recreate all the project settings but its good that I'm doing it while still early in development and not further down the road.