Step 2. Start creating posts - just 20 posts! - Spam or posts that don't contribute to the forum will be deleted.
I guarantee you that's not going to happen. 20 legitimate posts aren't easy to create in just a few days.
Maybe, it wouldn't have been possible IF it was a business forum or a community blog, etc. It's a gaming forum and we all have been gaming since years. I can give examples of making posts.
Post 1. Introduce yourself in Introduction section.
Post 3-4-5-6: Reply to other's introduction's post.
Post 7-8-9: Share your gaming experience and also admire the other's post who've shared their experience.
Post 10-11-12: Post your gaming videos - Such as, I play Blacksquad, CS 1.6 and VCMP. My Channel has the videos. I simply have to post for the poeple to watch. it's a win win situation right?
Post 13-14-15: Ask some questions regarding gaming? Maybe PC specifications for new users? Or answer the questions asked. Such as tipcs and tricks? - I believe it's always helpful
And rest 5 posts, off-topic posts are being counted. so one can share their experience watching movies, reading novels etc..
I think, 3 days are very enough. Anyways, the competition lasts up to 20th May. It's too far! Make 2 posts a day from now for 10 days. It'd be 16th May. Still, 4 days will be left.
Just a side note: I've freelanced on many forums making 100 posts in 3-4 days.