Ohohoho.
It may be very simple at first, but it is very much more complicated than you think.
For example, the thing that you missed, tension, will be extremely mandatory as you progress in the game. Tension affects how often you auto-attack, and how much of the party gauge you will fill by result. If your party is doing poorly, you will be fighting an uphill battle. You can encourage your allies however, for normal tension.
The party gauge as well, is extremely important. Yes, you can revive fallen members with a section of the party gauge, however, that is not what you primarily use it. If you fill the whole bar up, it will allow you to use a chain attack. Chain attacks allow each person to use an art in succession. So if you want to, you could do a Break, Topple, Daze combo right there. However, whenever you use an art of the same color in a chain attack(or a characters talent art, which counts as every single color), you will multiply the damage done. So if you use 3 red arts, that last attack will do 3 times the damage. Furthermore, the higher the affinity that you have between the current party members and the higher the tension is, you will have the chances to add on more hits to that chain attack, and make the multiplier go higher. The talent gauge is also very useful for another thing as well. Thanks to smash, it is no spoiler that Shulk can see into the future. That corresponds into gameplay as well. Soonish, you will gain the ability to see the future. This means, that when an enemy is going to use an art that will kill you or do a ton of damage, Shulk will see it in a vision and you will get a couple of seconds to prepare for the attack. You can use a section of the party gauge to warn another party member and use one of their arts. If you aren't controlling Shulk and he is in your party, then you will primarily want to go to Shulk. However you could have another character heal, or raise their agility, or topple the opponent, and really anything to stop the vision.
As a piece of advice as well. To fill up the party gauge quickly, you need to fulfill a requirement of arts. For example, Back Slash, and Slit Edge raises the party gauge a ton if you hit the enemy in the back and the side, respectively.
Playing this game in the mindset of an MMO is really setting yourself up for failure. Trust me, I've been through this too. I totally see the connection, but you will need to treat Xenoblade as an entirely new beast. Else-wise, you will be stuck in battles, not thinking you are doing anything wrong, yet dying again and again.
There is a ton more depth that I haven't explored yet. Buffs, debuffs, spikes, auras, gems. But we can cross those roads later.
As another tip of advice. Eventually you will get a party member named Sharla. Sharla is a pretty terrible party member, and will even teach you bad habits, slow down battles, and make fights infinitely harder than they need to be. At the earliest opportunity, I recommend that you replace Sharla with another party member. Sharla is actually the reason why there is no dedicated healer class in Xenoblade X, so yeah.
Also, don't go out of your way to do all of the side quests right away. Pick up them, but just play through the story and explore normally. You will get a lot of side quests done just by playing. Doing exclusively side quests will burn you out on the game, and it will also make you horribly over leveled. So yeah. Pick up and do some side quests, but don't do all of them.
