You have to add
def applicationTagLib = grailsApplication.mainContext.getBean('org.codehaus.groovy.grails.plugins.web.taglib.ApplicationTagLib')

before
applicationTagLib.link.call(attrs, body)

But you can fix it, just change some parts.

1) import this:
import org.codehaus.groovy.grails.plugins.web.taglib.*
class BaseTagLib {...

and applicationTagLib.link.call(attrs, body) instead of out << link(attrs, body)

I try to do something like this with a tank but i failed. I don’t know how to shoot, how to do a physical projectile what hit the enemy. Could i ask you to post your code in AndEngine forum? It will help a lot of developers and future developers.

Thanks in advanced, Eddy