As far as I remember, in X-Com: Terror from the Deep, X-Com Apocalypse and also in UFO: Aftermath you are just put into a de facto situation. You have a base and a squad and some vehicles, and then there is just the prompt to equipp your squad and go to a mission since somewhere some aliens have been spotted. You are simply thrown in the situation. The games do not really explain much on how things came to this point. They went to the core of the game, the tactical mission.
Now in my opinion, in the TBS genre, as a designer, the thing that you have to care about most, is the tactical mission itself. Even without a tech-tree and a story, a tactical combats basic features should offer a great variety of actions and challenges.
Imagine you have only the tactical mission feature, no tech-tree, no story. What could you come up with in order to make combat interesting and challenging, give it twist and variety, enrich it with surprises and shocks?
You would come up with maybe hundreds of ideas. You could implement them all into one single mission without referring to any story or tech-tree.
But what if you were allowed to introduce these features gradually? You would want to introduce this features to create a feeling of increasing difficulty. In other words you would strive to create the illusion of progress.
At first you would decide on which features to keep as basic combat elements and which ones to be introduced later. You would try to figure out how and when to employ or reveal the remaining features and how this to do this in a merely dote-antidote fashion which creates the feeling that we climb onto new levels in the game. This activitiy is actually what creating a tech-tree is about. Posing new threats, presenting solutions, posing new threats, presenting solutions and so on... As you see, the tech-tree itself, already imposes sort of a story.
Embed this tech-story in a broader sci-fi narrative with a surprising final. And you have even a better game.
So we have three layers then, not more actually. Tactical Mission, Tech-Tree and Story. I strongly believe that the tactical mission is the basic layer, the fundament. Theoretically it contains all basic gameplay elements. But if we wish we can present these elements along a row of discoveries guided by a tech-tree. You could design the tech-trees quite differently and that would mean you can create different stories with the same tactical combat elements. It just depends on how and when you want to introduce them. You could merge certain research topics to shorten the game or split them to produce longer playing hours. As it turns out, tech-tree and story are rather form than content here.
I'd like to refer back to X-Com Apocalypse. X-Com had a tech-tree, which meant the designers preferred to not reveal everything at one time. They chopped down the bulk of features into smaller pieces which then would be gradually revealed. Nice effort to turn a bunch of features into a progressing sci-fi adventure. BUT on the other hand, the initial combat features were actually more than sufficient for satisfactory gameplay.
Remember the core tactical missions in X-Com Apocalypse... I mean the first few ones you were going through, at the very beginning of the game, when nothing yet had been researched and nothing had been yet really told about what was behind the story. The basic tactical mission was already rich and posed many challenges to the player. I wonder how much (in percentage) the initially presented gameplay features in tactical combat make up of the total number of tactical combat gameplay features. I think within the first "week" in the game, at least one third of them, maybe even more, were actually enabled for player use.
I argue that the basic tactical mission could have been a stand-alone one and would have been quite entertaining without any tech-tree and story.
But what made these missions already so good? For example the basic spectrum of unique and challenging aliens types we encountered: I mean especially those without guns and grenades (remember the Hyperworm for instance). They couldn't shoot, instead they had surpising features. And all of these features were functional. They were meant to exploit certain attributes of our units, their mental or physical powers, their gear, their weapons and accessories. And they were meant to thoroughly put to test the ways in which we tried to overcome AI or how we'd strived to manage the units within the constraints of game physics and environment. Last but not least they were based on simple techniques and tricks to surprise the player and make him doubt his chances to succeed.
For example some aliens had metamorphosis features as the surprise element: The Hyperworm "giving birth" to smaller worms. The brainsucker pod, rather perceived as a grenade, turned into a brainsucker. But the chain could go quite far: We were even more surprised to see a brain sucked out and our unit starting to shoot at its own squad members.Then we had an alien that was itself designed as a weapon. This skyblue alien, a walking bomb, running at us at high speed. A good example for creating shock at the first encounter. Once we understood what it could do to us, the shock turned into suspense to last throughout all missions of the game.
See how much gameplay and variety is already there... And I haven't yet mentioned the armed aliens, for example the andropod. Add now the features of the humans: What they could do, what could happen to them etc... add also the terrain and building features.
Quite a lot, uh?
What I want to say is, even without tech-tree and story, the basic tactical mission was already a high quality combat game.
Now, what I want to ask is: Do we have really investigated all our options iregarding core gameplay. Are we rushing into the tech-tree and story layers too fast? I think that the belief that we must have a tech-tree and a story to make the game better, causes us to consider the question of better gameplay as already cleared. But I think if we want to bring more interesting things into the game we should be able to focus on the nature of our engine, game physics etc in order to develope interesting gameplay features, without potential ideas being mutilated by tech-tree or story. Our task as designers should be to use tech-tree and story as supporting layers of satisfactory tactical combat gameplay. Not the reverse. I fear we could miss chances to develope better gameplay features because we think tech-tree and story will do this for us.
Let me put the question in another way: "What is the most surprising, challenging and entertaining stand-alone tactical mission that you can imagine for UFO:AI? Imagine it, but without referring to tech-tree, without referring to story. Just think what you would like to be able to do during a tactical mission. Just think what would be a cool challenge of an alien.
