Atomfall includes some standard RPG elements, such as asking you to make choices without telling you the complete consequences of each option. As a result, you could lock yourself out of some of the available endings, or you might miss buffs that become useful as you progress deeper into the game. So, when you reach a quest that asks you if you want to inject yourself with an unknown serum, it's understandable that you might hesitate in a world like Atomfall's.

Once you reach the Interchange and start powering up the data centers with atomic batteries, you open up more quests and opportunities. With the Interchange being placed in the middle of the quarantined zone, you can use it as a way to access each region, but only after you've opened up every data center. Otherwise, you'll be limited to which regions you can reach from inside. Additionally, you'll find notes and keys that lead to making more decisions.

What Dr. Holder’s Inoculation Does

Trusting The Man In The Cellar

Before you can make the decision about Dr. Holder's inoculation, you need to find him. He's in Wyndham Village, but you won't be able to reach him until after you start opening areas in the Interchange. Specifically, you need to power Data Center C, which opens up the Medical area that was locked down. Inside Medical, you can find a key to the church cellar in Wyndham Village. This is your key to finding Dr. Holder, and potentially receiving his inoculation, if you decide to take it.

You might've already visited the church, but if you haven't, speak with Molly first and purchase her atomic battery. This gives you a lead from Molly saying that she had another battery, but sold it to a vicar in Wyndham. If you're heading that way, being able to pick up another atomic battery is hardly a bad thing, especially since you need at least four just to power the Interchange's data centers. It simply makes sense to check off as many leads as you can with as few trips as possible.

When you're ready, head to the church in Wyndham. The first time you enter it, you happen to find the scene of a murder. Speaking with the vicar after talking to Molly gives you the option to say you'll stay silent about the incident in exchange for the atomic battery, to which he agrees. The battery is in a locked chest upstairs, and he gives you the key to it. Then, head to the cellar and use the key you got from the Interchange to open the cellar and find Dr. Holder.

Dr. Holder wants you to grab Sample One from deeper in the Medical area of the Interchange. In exchange, he'll offer you an inoculation. This inoculation gives you a permanent buff, increasing your resistance to infection, which is particularly useful when you face Ferals and swarms, of which you find many in the Interchange. When you consider how easy it is to get infected while fighting, the idea of additional resistance to it is tempting. As it turns out, there's no downside to receiving this inoculation aside from the effort required to get Sample One.

You Should Inject Dr. Holder’s Inoculation

There's No Downside

You get increased resistance to infection without any drawback, so it just makes sense to inject the inoculation. Ferals can already be frustrating to fight against, and getting the infection debuff on top of that is annoying, so having even a small amount of protection can go a long way. The only issue would be if you didn't want to look around Medical for Sample One, but since you'll need to spend a fair amount of time investigating the Interchange anyway, it's not difficult to grab it in the meantime for the sake of a buff.

Although it is often described as British Fallout, Atomfall has shown that it's a unique title that gives you a lot of freedom regarding how you want to approach quests, and the ability to make choices that impact your ending. Since it's a short game, it won't take long for you to explore different outcomes. However, for choices like whether you should inject Dr. Holder's inoculation, there's no reason to not make the same choice in every run of Atomfall, and accept the resistance it gives you.