Ok, I give you that. But the toxin guns are really late/end game weapons, most of the game you use other weapons. And there are many interesting ones, like the guided missiles. There are teleporters, cloaking devices or disruptor shields, you dont get any of them in xenonauts. And why are you saying there were no heavy or sniper weapons??? Of course there were. A couple of cannons and launchers and a laser sniper gun. You even had a jumping proximity mine and a sword :-)
I would be ok with goldhawk changing the ground combat or improving it, for me the best part of Apocalypse was the city management mode anyway. The alien invasions through the dimension gates and the following air fights were much more interesting than in xenonauts.
In xenonauts you get your invasion every couple of days with 5 squadrons, shoot them down and enter ground combat at the crash sites, 5 times after each other with very repetitive maps and battles. Then you maybe research one tech and the next 5 squadrons come. You repeat the same thing many many times and for me it just gets boring after the 50th crash-site-mission. But you need to intercept the downed ufos to get the money for your production, so you just go through the monotonous missions to fund your progress.
In Apocalypse there were more different mission types, not only you fought the downed ufos, but the aliens would just randomly appear in buildings in the city. And there were many different buildings, many of them multiple storeys high, each forcing you to adapt your strategy a little. Some of the other organizations in the city would even turn against you later in the game and you would fight their well-equiped soldiers too.
The economy in xenonauts is really simple as well. In apocalypse you would keep all the weapons of killed aliens, you could use them after research or sell them. I even think you were able to sell alien corpses. And you could make money producing weapons and then selling them.
Not to speak about the options to equip your aircraft with many different modules and weapon systems. How cool was it when you had 10 fully equipped annihilators built and invaded the alien dimension and fought about 20 or 30 alien ships at once?! And then came the alien dimension combat missions...
Xenonauts gives you the ground combat, while pretty good, for me it gets very repetitive really soon. The air-combat is a mini-game at best and that is pretty much all. There is so much more you could add to the game.
I wouldn't just buy an Apocalypse remake, I would fund it!