This also happens with other SDL2 packages in F25 repo.

> sudo dnf install cdogs-sdl
> SDL_VIDEODRIVER=wayland cdogs-sdl

C-Dogs SDL v0.6.2
Original Code Copyright Ronny Wester 1995
Game Data Copyright Ronny Wester 1995
SDL Port by Jeremy Chin, Lucas Martin-King and Cong Xu, Copyright 2003-2016

INFO  [MAIN ] [files.c:622] SetupConfigDir(): Creating config dir /home/sebby/.config/cdogs-sdl/... 
INFO  [MAIN ] [files.c:627] SetupConfigDir(): Config dir already exists.
INFO  [MAIN ] [cdogs.c:260] main(): Command line (1 args): cdogs-sdl
ERROR [MAIN ] [cdogs.c:381] main(): Could not initialise SDL: wayland not available

Any update on this?

I compiled a local version of SDL2 2.0.5 using the following deps and configuration:

sudo dnf install libX11-devel libXcursor-devel libXext-devel libXxf86vm-devel libXi-devel libXinerama-devel libXrandr-devel libXrender-devel libXScrnSaver-devel libusb-devel libxkbcommon-devel alsa-lib-devel audiofile-devel dbus-devel mesa-libEGL-devel mesa-libGL-devel mesa-libGLES-devel mesa-libwayland-egl-devel pulseaudio-libs-devel systemd-devel wayland-devel wayland-protocols-devel

> hg clone https://hg.libsdl.org/SDL SDL
> cd SDL
> mkdir build
> cd build
> ../configure
> make -j

Using my local version, SDL wayland backend works properly. It seems the source RPM spec doesn't resolve all dependencies properly, specifically one or more of the following:

wayland-devel wayland-protocols-devel mesa-libwayland-egl-devel

Interestingly, I had removed the local build of SDL2 and reinstalled offical SDL2-2.0.5-2.fc25.x86_64.rpm and can no longer repro the issue. Not sure what has changed, but since I can no longer reproduce it, its no longer a bug.

I had mistakenly used SDL_BACKEND=wayland env variable instead of SDL_VIDEODRIVER=wayland cdogs-sdl in my last two comments.  

This is still an open issue. 

> SDL_VIDEODRIVER=wayland cdogs-sdl
C-Dogs SDL v0.6.2
Original Code Copyright Ronny Wester 1995
Game Data Copyright Ronny Wester 1995
SDL Port by Jeremy Chin, Lucas Martin-King and Cong Xu, Copyright 2003-2016

INFO  [MAIN ] [files.c:622] SetupConfigDir(): Creating config dir /home/sebby/.config/cdogs-sdl/... 
INFO  [MAIN ] [files.c:627] SetupConfigDir(): Config dir already exists.
INFO  [MAIN ] [cdogs.c:260] main(): Command line (1 args): cdogs-sdl
ERROR [MAIN ] [cdogs.c:381] main(): Could not initialise SDL: wayland not available
Segmentation fault (core dumped)

I traced the error to the following function:

src/video/wayland/SDL_waylandvideo.c: Wayland_Available 
- calls WAYLAND_wl_display_connect which returns null.

Hope that helps.

I did more troubleshooting and tried running this simple program to test wayland connection.

#include <stdio.h>
#include <wayland-client.h>

int main(int argc, char **argv) {
  struct wl_display *display = NULL;

  display = wl_display_connect("wayland-0");
  if (display == NULL) {
    fprintf(stderr, "Can't connect to display\n");
    return 1;
  }
  printf("connected to display\n");

  wl_display_disconnect(display);
  printf("disconnected from display\n");

  return 0;
}

The call to wl_display_connect also failed in this case. 

Oddly enough, the loginctl reports that I'm using X11 session even though I explicitly select GNOME session (not GNOME on X.org) on the login screen.

> loginctl show-session 3 -p Type
Type=x11

Therefore, this no longer appears to be SDL2 related issue.

The problem with Gnome failing to start Wayland session is reported by another user here:

https://bugzilla.redhat.com/show_bug.cgi?id=1403512

My hw configuration also comes with Intel integrated and Radeon discrete graphics in my laptop. With the workaround radeon.modeset=0 in grub configuration, Wayland session start successfully and so do SDL2 based apps.