Hello, I have a small predicament and wanted to get some input from others on the subject. A game uses RTA, due to a lack of designated rules, despite the game having an in-game timer. Would it be a good idea to change the rules to use IGT in order to eliminate loads, or stick with the current (albiet undefined) ruleset?

This is not an answer anyone here can give you. All we can provide is probably "rule of thumb" type things to consider.

I personally find a lot of communities fall into a trap of automatically accepting IGT as the best way to time their game without actually understanding what comes with using IGT. They think "IGT is always the most fair way to time my run, so we must have to use it." Just because a game has an IGT, doesn't mean that IGT is actually good for speedrunning or playing a game in a competitive environment. Let me break it down through some examples I've encountered over the years (all of this is obviously my opinion):

RTA has it's benefits and it's downfalls. On one hand, it's universal and even across all who use it when running a game - 1 minute of real time for me is the same as 1 minute of real time for you. A downfall of RTA is that, especially on modern consoles and PC where hard drives and SSDs play a factor, different hardware can result in different game speeds. For example, my PC uses an SSD, yours uses an HDD. For me, a game's load screens last for 2 seconds, but for you, the load screens last for 5. Obviously this creates a scenario where RTA is even for both of us, but my time is automatically faster because I can spend more real time playing, while you spend more real time waiting for loads. In a scenario like this, it can be tempting to use IGT because if IGT doesn't count load screens, now you have an even playing field.

But IGT can sometimes not be perfect either. The biggest downfall of IGT for me is how it handles deaths/continues. For example, say dying in a game and pressing "Continue" brings you back to the last auto-save point. Doing so resets the IGT to what it was at that auto-save. In other words, dying essentially allows you a free retry at a portion of the game because that time is removed from your IGT. This creates a moderation nightmare because it would make sense to ban this type of behavior, but then you're banning deaths. If your game is challenging or has high difficulty choices, banning dying could result in a huge barrier of entry that isn't fair to inexperienced runners. So then you try and ban intentional deaths. But how do you define an intentional death? Could a run slowly take damage in nonchalant ways that make a death seem unintentional? Then you decide to say that every death is an automatic 5 minute penalty, but that's 100% arbitrary and may not apply to all cases depending on how far back an auto-save reload takes you.

See how this is becoming nearly impossible to define? This is just one example, there are others you could do to. If pausing a game stops the IGT, how do you handle that? Can you only pause for a max amount of time before your run is invalid? What should that time threshold be? Would someone pausing every 30 seconds for the maximum allowed time be okay? Again, you find yourself essentially building decision trees and logical steppers to try and define rules around using IGT instead of just using a different timing method. Some games can do this because the impact is minimal (like original Sonic games using IGT but the rules say you can't idle too long on the screen between levels. It's not perfect, but it's better than RTA in that game where playing worse is actually faster, so RTA is just terrible), but most game should avoid these types of arbitrary rules.

While these are real examples that I've come across, one other example is that I know of a game where "intentional crashes are forbidden, but unintentional crashes allow you restart at the last auto-save and replay the run with no penalty." This rule seems really fair, but it's absolutely asinine in my opinion, because now you're forcing the mods to determine and extrapolate runner intent behind their actions. It's impossible do that, because unless something is egregious like a HESS crash in Majora's Mask, it's incredibly hard to tell what intent was for a runner. This game was loaded with rules like - "If continue is pressed on death screen RTA time will be used rather than IGT likewise if left idle on death screen". This is also an example of a horrid rule that exists only to try and justify the use of IGT. Pressing "Continue" on the death screen forces you use IGT (a penalty of around 30 minutes on average), but if you hit "Retry" it's okay because it may reset the IGT, but it does so without restoring your items used prior to the death. It's just asinine to try and differentiate this, because sometimes if you die and don't get your items back, a strat literally becomes impossible. This essentially means your run is dead because RTA is a 30 minute penalty. Even if the death only lost you 30 seconds RTA, hitting "Continue" to try it again is an automatic 30 minute penalty, essentially forcing all runs to be deathless at a high level of play. This game has multiple difficulties and the highest difficulty has 7.5% the runs compared to the lowest difficulty - one factor could be this rule that essentially forces all runs to be deathless, even if your RTA timeloss is minimal.

My rule of thumb is that your rules should never justify your choice of a timing method; your timing method of choice should be based purely off the behavior of it within the game, never off of some idea of "fairness".

The TLDR is that using RTA is not always the fairest approach, but sometimes it's just the best even if an IGT exists based on how the game behaves around that IGT. RTA can be finessed to use variables and other things to distinguish hardware differences so that way people can at least filter down hardware differences to correlate to the version they play on for the most fair individual comparisons. Sometimes doing that is better than defining rules that are loaded with arbitrary rules, or lots of "if this condition, then this action" rules because those rules become impossible to maintain in the long run of moderating a game.

In my opinion, IGT should only be used if it's consistent in removing loads, doesn't mishandle deaths or other retry scenarios, and can't be manipulated through the pause menu. In other words, you need to make the call on whether the game's handling of IGT is consistent and manageable without needing to build exception scenarios around deaths, crashes, pauses, retries, etc., or if it's better to concretely define RTA rules and stick to those, even it means creating variables or other things to account for differences in anything that could effect RTA. It's a game by game choice, it really depends on the game.

Most IGT timers I've seen in games are unfortunately very flawed and not good and fair to measure speedruns. But since it varies from game to game how it is implemented, there is no definitive answer and Timmiluvs pointed that all out very nicely. I'd say that you should always consider IGT as an option if the game has it but please test it before just blindly using it. Check out how the ingametimer works, what counts, when it stops or even resets, then make a decision based on that.