Three common measures used to evaluate effectiveness

Three common measures used to evaluate effectiveness (CAC's, Social media traffic, Mobile markets)

Key Performance Indicators (also known as KPIs) are a common way to measure how effective something has been. This can mean a whole lot of things depending on what you want to be effective - you could aim at returning customers (current clients)  or want to grow your audience on a specific platform or want to learn more about your audience (age ranges, themes, pricing etc) 

A KPI often used is Customer Acquisition Cost (also known as CAC's). 
CAC is a value that is worked out by adding (the total cost of marketing expenses and the total sales expenses) all divided by the number of new customers acquired. This KPI compares the amount you are spending to the total customers, if its less customers then they become more expensive, if its more customers then they are less expensive.

A different set of KPI's are often used for Social media traffic and Social media conversion rates.
Social media can be a great way to build a brand. By using various social medias you can have awareness for your brand in several different ways. It can be an eye opener to look into how many different social medias there are from Youtube, Twitter, Facebook to LinkedIn, TikTok, Pinterest and Reddit. Each social media has a very different presence online and a very diverse cast of audiences.
For example, TikTok is pretty recent in regards to youtube but both do video based content. TikTok limits the amount of time a video can be to a minute (some accounts being granted early access to longer forms (up to 3 minutes)). Whilst Youtube allows up to days worth of content (once the account is verified - otherwise its limited to 15 minutes).
Due to this and several other factors the audience are very different. It would be advisable to put content appropriate to that platform's demographic on the platforms you think are ideal for your target market. You can also cross pollinate to different platforms and have that as part of your branding - this allows for potentially better communication with your audience and allow you to have a bigger presence online.

Mobile Marketing KPI's.
I mentioned TikTok and Youtube above, both are apps in the mobile space, but if you make content for them you should try to accommodate for different phones. This doesn't mean you have to design an ad per phone (that could take years!). Instead try to think about how the phones operate. For example;

• Can you turn the video landscape for better viewing?
• Can the viewer scan qr codes to go directly to your game?
• What market places can you sell on for those devices?

Ever seen trends happen like a bunch of ads all doing the same sort of game (for example match 3 games)?
This is a good example of an easy to make game that is often spammed as an ad to audiences as they can have a wide potential market.
Instead You could make meta commentary about this as a way to discuss the topic directly with your audience. This could generate discussion of You as a brand and your games. Be careful though as this can be Good and Bad depending on how others discuss your ads.

I researched this via this article https://www.impactplus.com/the-10-marketing-kpis-you-should-be-tracking (Edgecomb, 2021)

Edgecomb, C., 2021. The 10 marketing KPIs you should be tracking (updated for 2021). [online] Impactplus.com. Available at: <https: www.impactplus.com="" the-10-marketing-kpis-you-should-be-tracking=""> [Accessed 9 July 2021].</https:>