Shortly after Operation Wallclimber in Armored Core VI or AC6, two new menus will become available: the Arena and OS Tuning.
In the ranking simulator known as the Arena, you can battle opposing AC. There are no healing or additional enemies; there is only a fair one on one fight. Here you can climb in the ranks.
At this early stage of the game, you can only battle F-rank enemies but as you complete more missions, additional enemies will become available. And you should undoubtedly clean the arena as soon as new AC fights are made accessible.
Not only is this fantastic practice for some of the hardest fights in the game, but you're also rewarded with credits with no maintenance or ammunition costs. The most important thing is that you're also awarded with a resource that is essential.
OST Chips are a resource that may be used to upgrade your AC in a number of different categories. You may do this through the OS Tuning menu, where you'll find a number of upgrades. These menus provide upgrades that are geared for more experienced gamers. For instance: few players will ever find they need to Aim Manually or to enter a mission while overburdened. So avoid wasting your points on useless upgrades that you won't use.
Nevertheless, by pressing triangle or Y, you can get back your used OST chips. You will need to pay 4000 credits to undo each OS upgrade. But some of these upgrades will make any player stronger regardless of their skill level.
Let's go through each category now and pick out a few priorities:
The Boost Kick function is one that I would unquestionably recommend everyone to unlock. If you have this turned on, pressing L3 again at the end of your assault boost will allow you to do a melee slam. This is really fantastic. While you're hard locked onto an enemy with target assist and it's the perfect capstone to an enemy who is almost guard broken because it saves you having to expend ammunition on breaking their guard and it leaves your ammunition free to capitalize on their broken guard instead.
Once unlocked, Expansions can be slotted into your AC’s assembly. And while you can only equip one Expansion at a time, you can invest into unlocking multiple charges of each Expansion. However, note that unlocking multiple Expansion charges is expensive and there's a cooldown period after using an Expansion charge. By default, Expansions are activated by pressing L3 and triangle, or Y, simultaneously. However, you can switch these controls in the game settings. Personally, I prefer type B, which allows activation with L3 and R3, which is easy to remember. When you’re just starting out, it is easy to forget to use your Expansions. So if you're new to the game, then I'd actually recommend that you choose a passive expansion instead. For example, Terminal Armor - once equipped, it's always active and will always keep you alive at 1 AP for a few more seconds in a situation where you would have been destroyed. This can give you valuable time to heal or just survive a little longer. I really can't overstate how useful passive upgrades are in an input heavy game like Armored Core 6.
After Terminal Armor, I'd recommend getting the early ranks of many passive upgrades. You can't go too wrong here, and by investing in passive upgrades, you can rest assure that your AC is becoming more powerful.