Use an EC2 Auto Scaling group across at least two Availability Zones to scale based on demand and Place a Network Load Balancer in front of the EC2 fleet to handle Layer 4 connections are the correct choices for this scenario.

Use an EC2 Auto Scaling group across at least two Availability Zones to scale based on demand provides resilience against an Availability Zone outage and it automatically adjusts instance count to match player load so costs fall during off peak hours. Place a Network Load Balancer in front of the EC2 fleet to handle Layer 4 connections is appropriate because the Network Load Balancer operates at Layer 4 and it supports UDP so it can forward the game traffic without terminating or inspecting application layer payloads.

Switch to smaller instance types and increase the number of instances in the same Availability Zone is incorrect because keeping all instances in one Availability Zone does not improve fault tolerance and it will not automatically reduce costs without an automated scaling mechanism.

Front the service with an Application Load Balancer is incorrect because the Application Load Balancer works at Layer 7 and it does not support UDP so it cannot handle the game connections.

AWS Global Accelerator is incorrect as a standalone solution because it can improve routing and global performance but it does not provide multi Availability Zone compute fault tolerance or automatic cost savings from scaling and it introduces additional cost.

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