You can put anything in the text fields there - then You'll be moved to main menu screen anyway.
As for me - quite cool idea! Enemy sending their troops and you need to place your own units to prevent entering the bottom area. And the rock-paper-scissors mechanics - nice! :)
Few things I'd consider:
- consider adding a few words (or maybe a tutorial level, as separate main menu option?) on the controls. When you launch the game for the first time, it's not intuitive what to do. I started clicking on the icons at the bottom, pushing arrows and WASD, but only after I accidentally clicked the warrior it turned out that I can move him :)
- a simple popup at the very beginning of gameplay, that tells who-wins-with-who would be great
- It's probably just me, but I'd like to have some hints on the icons below (the catapult, fence etc) - I dont know when or how to use them, which ended up me clicking it every now and then during gameplay, which resulted in sometimes launching the catapult, but sometimes not :P
And one more thing - gameplay is already engaging :D
I thought to myself "OK, I'll give it a try, and that's it" - but it makes me come back ;)