These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.33 s (backtrack: 0/20).

[ebuild  N     ] media-libs/libogg-1.3.6::gentoo  USE="-static-libs" 430 KiB
[ebuild  N     ] media-libs/alsa-topology-conf-1.2.5.1-r1::gentoo  USE="-verify-sig" 12 KiB
[ebuild  N     ] media-libs/alsa-ucm-conf-1.2.16.1::gentoo  USE="-verify-sig" 83 KiB
[ebuild  N     ] media-sound/fluid-soundfont-3.1::gentoo  USE="-timidity" 131676 KiB
[ebuild  N     ] media-libs/alsa-lib-1.2.16.1::gentoo  USE="python -debug -doc -verify-sig" PYTHON_SINGLE_TARGET="python3_14 -python3_12 -python3_13 (-python3_15)" 1104 KiB
[ebuild  N     ] acct-group/nobody-0-r2::gentoo  0 KiB
[ebuild  N     ] app-eselect/eselect-timidity-20110513-r1::gentoo  2 KiB
[ebuild  N     ] app-eselect/eselect-mpg123-0.1-r1::gentoo  0 KiB
[ebuild  N     ] media-libs/opus-1.6.1::gentoo  USE="-custom-modes -debug -deep-plc -doc -dred -hardened -osce -static-libs -test" CPU_FLAGS_X86="sse" 10228 KiB
[ebuild  N     ] app-arch/7zip-26.04::gentoo  USE="symlink -jwasm -rar -uasm" 3064 KiB
[ebuild  N     ] media-libs/libmodplug-0.8.9.1::gentoo  234 KiB
[ebuild  N     ] media-sound/mpg123-base-1.33.7::gentoo  USE="alsa ipv6 (-coreaudio) -int-quality -jack -nas -oss -portaudio -pulseaudio -sdl -verify-sig" CPU_FLAGS_X86="sse (-3dnow) (-3dnowext) (-mmx)" 1100 KiB
[ebuild  N     ] acct-user/timidity-0-r2::gentoo  0 KiB
[ebuild  N     ] media-libs/libsamplerate-0.2.2::gentoo  USE="-test" 3242 KiB
[ebuild  N     ] media-libs/flac-1.5.0:0/11-14::gentoo  USE="cxx -debug -ogg -static-libs" CPU_FLAGS_X86="avx avx2" 1054 KiB
[ebuild  N     ] media-libs/libvorbis-1.3.7-r2::gentoo  USE="-static-libs -test" 1176 KiB
[ebuild  N     ] media-sound/lame-3.100-r3::gentoo  USE="frontend -debug -mp3rtp -sndfile -static-libs" CPU_FLAGS_X86="(-mmx)" 1489 KiB
[ebuild  N     ] x11-libs/libXcursor-1.2.3::gentoo  USE="-doc" 286 KiB
[ebuild  N     ] media-sound/timidity-freepats-20060219-r1::gentoo  25188 KiB
[ebuild  N     ] media-libs/libsdl2-2.32.10::gentoo  USE="X alsa dbus haptic joystick opengl sound video (-aqua) (-custom-cflags) -doc -fcitx -gles1 -gles2 -ibus -jack -kms -libsamplerate -nas -oss -pipewire -pulseaudio -sndio -static-libs -test -udev -vulkan -wayland -xscreensaver" CPU_FLAGS_X86="mmx sse sse2 sse3 -3dnow" 7452 KiB
[ebuild  N     ] media-sound/alsa-utils-1.2.16:0.9::gentoo  USE="libsamplerate ncurses nls -bat -doc -ieee1394 (-selinux) -verify-sig" 1629 KiB
[ebuild  N     ] media-libs/libsndfile-1.2.2-r2::gentoo  USE="alsa sqlite -minimal -test" 714 KiB
[ebuild  N     ] media-libs/sdl2-net-2.2.0::gentoo  USE="-static-libs" 8504 KiB
[ebuild  N     ] media-libs/sdl2-image-2.8.8::gentoo  USE="gif jpeg png tiff -avif -jpegxl -samples -static-libs -test -webp" 6714 KiB
[ebuild  N     ] media-libs/libsdl-1.2.78::gentoo  USE="X alsa joystick opengl sound video -test" 487 KiB
[ebuild  N     ] media-sound/fluidsynth-2.5.7-r1:0/3::gentoo  USE="alsa dbus ipv6 openmp readline sndfile threads -debug -doc -jack -ladspa -oss -pipewire -portaudio -pulseaudio -sdl (-systemd)" 2124 KiB
[ebuild  N     ] media-sound/timidity++-2.15.0-r6::gentoo  USE="X alsa ncurses -Xaw3d -ao -emacs -flac -gtk -jack -motif -nas -ogg -oss (-selinux) -slang -speex -tk -vorbis" 1332 KiB
[ebuild  N     ] media-libs/sdl2-mixer-2.8.2-r1::gentoo  USE="fluidsynth midi mod modplug mp3 timidity wav -flac -gme -opus -playtools -stb -tremor -vorbis -wavpack -xmp" 5861 KiB
[ebuild  N     ] media-libs/smpeg-0.4.4-r12::gentoo  USE="opengl" CPU_FLAGS_X86="(-mmx)" 321 KiB
[ebuild  N     ] games-arcade/rocksndiamonds-4.4.1.3::gentoo  203708 KiB

Total: 30 packages (30 new), Size of downloads: 419200 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by games-arcade/rocksndiamonds-4.4.1.3::gentoo
# required by =games-arcade/rocksndiamonds-4.4.1.3 (argument)
>=media-libs/sdl2-mixer-2.8.2-r1 timidity