Hi Gabeeg
Your opponent seems to be aware of how to keep his force alive
Smoke use is crucial.
Be aware of your unit's ability to deploy smoke, or their ability to see through it (Vision 40 or more = thermal imaging, which 'sees' through smoke)...and also where possible, the abilities of your opponent's units.
When you are being attacked, popping a smoke grenade is a great way to cut down the LOS (Line Of Sight) of you opponent to you...perhaps meaning you can escape to cover, or just fight with one enemy, rather than three or five.
If you have to move over open ground, as your opponent did, then buying units than can provide smoke cover for those crucial 2 or 3 turns is very important.
Mortar units are great for this...small mortars 50, or 60mm are not great for killing troops but can save many lives with a good smoke screen eh. Often there are integrated with infantry units are are not included in any 'rules' for arty buys.
Remember, if you saw a perfect spot for an ambush...if your enemy is any good at all...then so did he :-) You cannot expect him to just hand you the game by walking into it now, can you?
Z-fire is indeed 'sprayed' around when it is used through smoke, but as long as the MGs or HE fire is getting close to troops, especially if they are moving fast out in the open (behind the smoke obviously), you may well be able to suppress them enough to stop their forward movement...then perhaps your opponent will run out of smoke ammo to cover them...and then it game will change.
One thing...there are players here who totally over use z-fire and IMO ruin the battle.
There are no 'rules' about this per-se...but I tend to make an agreement with my opponent that z-fire is to be kept to 'reasonable' levels.
IMO z-fire out beyond actual LOS (vision level for the actual battle) is very gamey. The player is then using 'eye-of-god' to know where enemy unitsd are and then (usually without any real ability to direct that fire by radio etc) shooting z-fire perfectly into troops concentrations that he could even see if there were no smoke (or trees, or buildings or hills etc).
I tend to restrict z-fire to area fire weapons like MGs and SP guns and try to limit the amount I use so it works tactically, but does not dominate the game.
Yes...you should always keep a few rounds in the weapon for op-fire during the opponent's half of the turn.
You unit will op-fire if you did shoot all your allowance during your phase of the turn, but the op-fire will be very limited.
It is always best, when expecting your unit to have to take fire in the next phase, to leave as many shots as you can for op-fire.
Also, it seems to me that op-fire is often more dangerous and casualty-causing than standard direct fire. That is just a feeling I get though, no data on that
Anyway...learn to use smoke to cover your advance...that's why it is included the game. Then learn to deal with it's use by you opponent.
It is not gamey...it is very normal behavior, both in the SP game and as far as I am aware in real life warfare as well.
Good luck!!
walrus