Well, the topic is called “playground”, so doesn’t hurt to check things out, just need some GTK4 apps to check out, so far most I tried our bound to/or require rust. (and for those I need to switch to nightly)
EDIT: First let’s create a recipe for it here. 
Haruna 1.8.1 is released, not to the Haiku public (so far we got enough media players 
). For this a patch has been upstreamed to fix building for system not supporting DBus. Since this is one I’ve been following for a long time, I keep up with upstream releases.
Playing around with Qt6, 6.11.0 had some weird font issues here, so with the new release for 6.11.1 I thought I’d give it a spin again. Looks like that font issue is resolved. 
With Qt6 and KDE mostly on par I did some digging into GTK4, for this updated glib2 to 2.88.1, GTK4 to 4.22.4, libadwaita to 1.9.0, added a few local packages required for building GNOME packages in Terminal.
Since some of the sources I’ve tried require rust, I do most of these tests in nightly (TLS fix not in beta5).
So far in the last days spend time on Fractal (still has an issue with one of the rust crates where we don’t support memfd), Ghex and Gitte up and running.
For Gitte I always ended up with: undefined reference to iconv_open while linking, using RUSTFLAGS eventually did the trick there.
export RUSTFLAGS+=“-L/boot/system/develop/lib -liconv”
Giite got updated to 0.5.0, still struggling with GTK4 though, keystrokes repeat when pressed ending up pressing p to ppppp…
EDIT: played around a bit with a few GTK4 themes (css files), for the UI
Endless Sky v0.11.2-alpha:
Endless Sky is a space trading and combat simulation video game. Mostly, I’m reviewing keyboard options and basic game functionality. Seems to work good on Haiku.
Thanks to @X512 who pointed me to the “correct” solution, GTK4 is now “fixed” and keystrokes are working fine (no repeats after keydown - which was my own fault to start with) 
Keypunch 6.3 up and running (these are all build from Terminal)
Hedgewars 1.1.0-git (c8904b103) 
:
Free Worms-like turn based strategy game. Ported to Haiku by PepperSawce. I just did some plumbing.
About:
Tentacle Terror scenario:
UFO training:
Mission 1: First Blood:
Game Combat (quick game vs. computer):
Grenade training:
Good job for this port
Nice, but can you actually play something, IIRC we only got as far as showing the menu back then.
Yes. Added a few more photos…
webkitgtk for GTK4 build (thanks for the help there @waddlesplash - for the build process), MiniBrowser process crashes on launch, but hey … it’s a start!
Aside from that, played around with some more themes out there:
EDIT: another one for the list, Tuba now an alternative for Tokodon
Little translator app, no need to hunt the web anymore (also works on beta5)
Dialect-2.6.1:
