TftD was much harder because of the damn corals and alien bases were a nightmare. While the Heavy weapons crew doesn't work quite as well (as in enemy unknown), as corals don't blow up quite as well as buildings for LoS/LoF purposes.
The scout/sniper team works quite effective still in TFtD- snipers take up position (near troop carrier), and kneel and stay in position until a better position is needed to cover the scouts. The scouts sweep the map, if alien discovered the kneeling sniper takes him out. Scouts also end turn in kneeling position (try not to get your scouts killed- once you get to +60 reaction stats and good Time units you'l be doing just as much damage during alien turns with reaction fire). If you use one scout paired with a sniper only move scout about 2 squares each turn then end turn kneeling (this improves reaction fire as reaction fire= time units X reaction stat). Better system is to pair two Scouts together with one sniper covering (one is resting scout and they alternate each turn). In this case you can move the first scout 6 squares forward and then 3 squares backward (if alien not discovered), just make sure you end up next to the resting scout after moving backwards 3 squares; the resting scout will still have all his time units. This way the alien will have to move atleast 3 squares to get to your scouts- this means the resting scout will get a chance to react fire.
Use a grenadier- prime grenades in early part of mission and then throw them to your buddies to pick up and use on the front (aka grenade relay). Also allocate one 'squadie' to be 'Ammo mule'- he carries all the rockets/extra grenades etc.
When choosing roles- any one with reaction stat of >50 should be scout; firing accuracy of >60 should be sniper; heavy weapons need >60 and strength >40; grenadier aim reaction stat >50 (if you want to use him in front lines; otherwise not needed as he can stay at rear and use grenade relay), and reasonable strength stat >40, Ammo mule strength >40.
Another tip is to use smoke grenade or what ever they are called in TFtD ( I preferred ufo enemy unknown), prior to deploying from the troop carrier (Triton from memory I think it was called
). You then deploy on turn 2 under smoke cover. Saves your guys from getting hit in the head after taking one step outside troop carrier. This is because during first turn the Aliens (who haven't moved yet), will have max time units so expect high reaction fire.
Also everyone should act as medic (equip every team member with a medical kit).
Also don't reload after taking casualties. The games is more exiting this way.
after watching youtube videos of this game I really want to play it. 
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Play UFO enemy unknown- it is much better than TftD. Works well in Dos Box 0.74. Just patch it to version 1.4. Also get "xcom utils" it adds quite a numbers of things and improves several weapons. For example the heavy laser is not shit anymore. And 'High explosives' can now breach UFO walls- this opens up a whole new tactical aspect to the game as you don't need to take the doors which are usually camped by Aliens ready to react fire etc...
