The description sounds exactly like Tikal (1999), although Tikal seems to be more focused on strategy, rather than short-term tactical decisions.
More info: http://boardgamegeek.com/boardgame/54/tikal
More info: http://boardgamegeek.com/boardgame/54/tikal
[1] http://boardgamegeek.com/boardgame/65244/forbidden-island