In a radial air-cooled engine, the starting process is extremely complicated figuring 10-15 steps before even engaging the starter.. Not to mention they had a phenomena called Hydraulic Lock after the engine was shut down.. Since radial engines use copious amounts of oil, the oil leaks into the cylinders after shut down and needs to be drained before a restart can be attempted. THIS CANNOT BE DONE WHILE IN THE AIR and requires a mechanic to perform..
Shutting down a radial in flight is as simple as mixture to cutoff and mags off. Restarting is basically the opposite mags on, then bring the mixture up, since the prop is windmilling the engine (assuming you're not in feather) you do not even need engage the starter, and the engine driven fuel pump will still be turning as well. Although if the engine has been off long enough to cold soak, (more then a few minutes at altitude) you may need primer and boost before bringing the mixture up to restart it as well.
Hydro-lock (which is hydrostatic, not hydraulic) can only happen after sitting for an extended period of time, and with planes that are flown frequently it is not very common. In almost 2 years at my current job (where we fly dozens of P&W R2800s everyday) I've never heard of a hydro-lock incident.
It is true that starting a big radial is more complicated then starting turbines, (especially when cold) but it's not that bad. Heck, if I can do it, it can't be that hard.
Our typical cold start procedure (without going into the whole aircraft configuration checklist) is basically: boost pump on low, engage starter, spin through 6 blades (4 crankshaft rotations with the gear reduction) to check for hydro-lock, 6 more blades just for for pre-oil, at 12 blades flip both on mags then hit the primer and boost, (at this point it'll sputter to life) keep on the primer as you slowly bring the mixture up to auto-rich, when you see a slight drop in RPM, release the primer and she should be running smooth. Of course the number of blades we spin through before start varies with how hot or cold the engine is.
Back when I still played AH frequently, one of my complaints was that the engine management was way over simplified. People flying around at full military power constantly without killing/overheating engines, and crazy rapid throttle changes (always at full RPM) without occasionally blowing cylinders and backfiring is just not realistic. Not to mention managing mixture, cowl flaps, oil cooler doors, etc... etc..
I mean HTC has gone to great trouble to recreate realistic flight modeling and damage modeling. But realistic engine modeling seems to be forgotten. When I played it was always just "E" for start, prop at full RPM, firewall the throttle, and forget about it until you needed to slow down. Also I seem to recall that the water injection on some planes seemed to have unlimited water.