Have a read of these threads, they mention game server hosting on Amazon -
AWS Free Usage Tier
Amazon cts server
I can't see on the linked page what the server specs are?
- 750 hours of Amazon EC2 Linux Micro Instance usage (613 MB of memory and 32-bit and 64-bit platform support) – enough hours to run continuously each month*
 
- 750 hours of Amazon EC2 Microsoft Windows Server Micro Instance usage (613 MB of memory and 32-bit and 64-bit platform support) – enough hours to run continuously each month*
 
- 750 hours of an Elastic Load Balancer plus 15 GB data processing*
 
- 30 GB of Amazon Elastic Block Storage, plus 2 million I/Os and 1 GB of snapshot storage*
 
- 5 GB of Amazon S3 standard storage, 20,000 Get Requests, and 2,000 Put Requests*
 
- 100 MB of storage, 5 units of write capacity, and 10 units of read capacity for Amazon DynamoDB.**
 
- 15 GB of bandwidth out aggregated across all AWS services*
 
- 25 Amazon SimpleDB Machine Hours and 1 GB of Storage**
 
- 100,000 Requests of Amazon Simple Queue Service**
 
- 100,000 Requests, 100,000 HTTP notifications and 1,000 email notifications for Amazon Simple Notification Service**
 
- 10 Amazon Cloudwatch metrics, 10 alarms, and 1,000,000 API requests**
 
Tucked away in the FAQ's 
Quote:Micro Instance
613 MB memory
Up to 2 EC2 Compute Units (for short periodic bursts)
EBS storage only
32-bit or 64-bit platform
I/O Performance: Low
API name: t1.micro
Quote:One EC2 Compute Unit provides the equivalent CPU capacity of a 1.0-1.2 GHz 2007 Opteron or 2007 Xeon processor. This is also the equivalent to an early-2006 1.7 GHz Xeon processor referenced in our original documentation
Why don't you try it and report back how it went!