It is not really a spin if forced with rudder. In a developed spin the bank should be maintained by the difference in lift (inner wing more stalled than outer wing) and difference in drag should maintain the yaw rate (again, inner wing more stalled than outer wing). Introduce yaw while stalling and this should induce spin if the aircraft is sensitive to it (some aircraft just won’t, generally if it is hard to get into, it is hard to get out, so spin is strictly prohibited on some types).
What would aggravate the spin (as already mentioned):
- Aft CG
- Power
- Left spin for clockwise rotating propellers
I do flat spins all the time in my Pitts. For that airplane spinning to the left and adding lots of throttle once the spin develops flattens the spin. Outside aileron accelerates it. MSFS, X-Plane, DCS—all get it so wrong that it is pointless to even try. This also includes vanilla spins and snaps. Attempting anything post-stall in any of these sims is just practicing bad, if not fatal, technique.
Even on Level-D Full Flight Simulators certified for UPRT including post stall, the post stall stuff is just an extrapolation. I don’t know if still the case, but the default C172 also displayed quite wonkey spin behavior.