The two mobile ones that had me hooked were Puzzle Quest (RPG strategy) and Dungeon Raid (Roguelike strategy). These are both hybrid games that combine genres so maybe they don't count as strategy. But, they are both fun and addictive.
Stronghold looks awesome, never played it. I loved Red Alert. A game I released is similar to Red Alert named Land Air Sea Warfare, you might want to check it out.
I love AoE2, it was the RTS I had the most fun with, so many fun LAN games, I base some my game design decisions on AoE2. Homeworld was really cool too, I think it was the first of its kind. Although halo and half life are some of the best games ever, I wouldn't count them as strategy games.
Civilization Revolution 2 is fantastic, but everything is animated with no option to turn off animations, leading to quite a bit of wasted time and excess battery drain. But my other suggestion is Xcom, both are great games, but I think Xcom probably has the edge.