Royal Defense

Royal Defense is tower defence in its most established form: a road, a stream of enemies walking down it, and a set number of places you are allowed to build. The fixed build slots are what makes it a puzzle rather than a sandbox. You cannot wall anything off or reroute the path, so every decision is about which of a limited set of positions is worth spending on and what to put there. Four tower types — archers, mages, artillery and barracks — cover different jobs, and the barracks in particular changes the maths, because troops that physically block the road buy time for everything else to shoot. Heroes and spells sit on top as the answer to the moments where the towers alone are not enough.

Pick a level, then place towers on the marked build spots before and between waves. Each tower can be upgraded with the gold you earn from kills. Archers hit fast and cheap, mages handle armoured targets, artillery deals splash damage to groups, and barracks spawn troops that physically stop enemies on the road. Summon your hero and cast spells at the moments a wave would otherwise break through. Clear all waves to finish the level and earn stars.

Upgrading two towers is almost always stronger than building four. Damage scales faster than coverage in this format, and a fully upgraded archer tower at a corner beats three basic ones spread along a straight. Put barracks where the road bends, because troops blocking there hold enemies inside the firing range of everything you have built. Save your spells — the instinct is to use them on the first wave that looks dangerous, but the wave that actually kills you is always later. And read the incoming wave composition before spending: building artillery against a single armoured boss is money thrown away.