And in 2 days work, I have entered the fray:
For the record, GAF stands for Government Aircraft Factories, which at the time was basically in charge of indigenous fighter programs.
In this alternate timeline, Australia has built the YD-120 as an indigenous fighter-bomber for homeland defence. Due to local geography requiring long ranges capability, the YD-120 is one of, if not the heaviest entry to the IGF program.
The feature shown in the top right is basically a novel mix between an intake ramp for supersonic shock cone control and also to increase laminar flow over the wing at high angles of attack, increasing yaw control and also reducing the likelihood of aerodynamic wing-stall. (Also, it's been approved for the contest).
Aircraft used were Birdfarm's F-15, 16, 18, a ground object F-111 from YS Major and the afterburners of the F-111B from the 171st GAC pack.