Targetware 0.63 was an online combat flight simulator.

Targetware 0.63 was an online combat flight simulator.
The game always had a beta status and was free. You only had to
register, download the game (OS X, Windows or Linux), pick and
download the mods, connect to the main server running the mods
scenarios in loops, and fight online.
The mods were done by groups of players designing maps and planes for
different historical periods. These were then used by the Targetware
engine.
There were four main mods, Richthofen's Skies (WWI), Target Tobruk
(Mediterranean air war, WWII), Target Rabaul (WWII, Pacific), Target
Korea (?Korea). Each was regularly updated by the mod makers with new
planes and features, the most developed ones being Tobruk and Rabaul.
There were also other mods in various state of development, but these
never reached the playable online status.
The emphasis of Targetware was the realism of the engine and planes'
flight behaviour. Some planes were indeed very difficult to fly, just
like the real ones, and you had to manage things like fuel, engine
temperature, propeller pitch?and other stuff depending on the plane.
All that in a combat mission.
Could be frustrating for a beginner, but I've never felt such an
immersive environment in a game. Still have memories of some missions
and fights that made me sweat.
Graphics were good for the time, some of the last planes issued being
real gems. For example the C-47's cockpit, or the Mosquito, beautiful
work from the dedicated mods team.

Then in 2009 it stopped. The main server went offline. From what I
know, the main owner and maintainer of the Targetware engine faced big
changes in his personal life and could not afford maintaining and
developing the engine and server.

I kept the game with the latest updates of the mods that I had
preciously.
Here is the thing with Rabaul, Tobruk and Korea mods included. Don't
have Richthofen's Skies unfortunately. It is all configured to work
with a Saitek Cyborg 3D joystick.
It is still playable as a flight simulator, no more fights as you
can't connect to a server.

Will run on Mac OS X 10.4 and 10.5 on a PPC (runs fine on a PowerBook
G4 1.67 without pushing graphics too much), and very fine on Mac OS X
10.6 in Rosetta on a MacBook Pro 2.33.

Not much about Targetware left online now, the main site is gone, but
available on the Wayback Machine:
<https://web.archive.org/web/20080827192934/http://targetware.net/>

Here is also a page with some info and screenshots.
<https://rensg.home.xs4all.nl/tgtware/>

And the editor page on the Wayback Machine :
[https://web.archive.org/web/20080518082421/http://www.mk9sys.com:80/targ...][1]

Compatibility
Architecture: PPC (Carbonized) x86 (Intel:Mac)

[1]: https://web.archive.org/web/20080518082421/http://www.mk9sys.com:80/targetware.php (https://web.archive.org/web/20080518082421/http://www.mk9sys.com:80/targetware.php)