Balance the game

[sdiaz7]

This issue must be addressed after all new enemies have been integrated, and before release.

After so many changes at both enemies and towers, the game has become rather unbalanced. It is mandatory that we achieve some sort of balance before the release, if we want to be able to present a good DEMO.

Things that should be fixed:

• Adjust tower health / Enemy attack: at this moment, it takes 40 hits for an enemy to destroy a tower. Ideally, it should take 1 to 5 hits.
• Adjust enemy health: most enemies can't stand more than one hit. They should be made more durable.

Feel free to add any other balance problem you notice...

Issue is being developed and discussed at dev_issue192

[sdiaz7]

Branch merged into DEV after approval. Issue closed and moved to DONE.