Tottal Annihilation seems pretty good.
or you can try downloading Command & Conquer Tiberian Sun.since EA released it for free
[url=http://www.fileplanet.com/210105/210000/fileinfo/Command-&-Conquer:-Tiberian-Sun-(Full-Game]http://www.fileplanet.com/210105/210000/fileinfo/Command-&-Conquer:-Tiberian-Sun-(Full-Game[/url])

Yeah. Original war. It is sprite-based, its concept is quite uncommon (you have never played anything like it,) and its campaign's got branching story with choices and consequences. If you are after a singleplayer RTS, you have GOT to grab this one. If he wants to play skirmish or muliplayer...

Listen to this Total Annihilation track. It compels youu!

You really, badly need to add Total Annihilation to your collection. It's amazing.

I'd also recommend Earth 2150. Another game with a lot of unique concepts that never really appeared in other titles.

Original War is outstanding, YES, but once the 2 fairly long campaigns the replay value is low.

Thus, I would go for Cossacks. It is very good (think AoE with thousands of units on the battlefield, 20 different factions or so, ...), and it has one of the best replay value I know of in a RTS (there are like 5 campaigns and 100 or 150 "independant" missions that are actually complex and well-done, IIRC.

Not all of those are RTSs. HOMM3, Age of Wonders, Conquest of the new world & Master of Orion are TBSs. Do you want recommendations from that genre as well?
In that case, I would recommend:
Battle Isle & M.A.X. (strategy) and also Jagged Alliance 2 (tactics)

Is Total Annihilation like C&C ? Judging from the pics it looks like C&C. I used to play Red Alert 1 for hours...

I was also looking at 4X games like SMAC (used to have the box, lost it long ago), but Call to Power isn't exactly my cup of tea : too boring, ugly UI plus the lack of soundtrack...

So yeah, Total Annihilation looks nice, the only question left is the replay value : how long's the main campaign/story and is there a scenario/map creator ?
I also checked TA:Kingdoms, what differences are they ?

Thanks everyone for your concern !

Not really. It's one of the first games to really break the C&C mould. You do have base building and dozens of different unit types (and literally hundreds in your army at once), but there are some very clear differences between that and C&C.

Highlights include:
- Outstanding orchestral original soundtrack.
- Option to give complex chains of orders to many units while the game is paused, meaning that you can focus on all aspects of conquest, defence and base / unit building all at once with no compromise.
- Commander and other mobile construction units mean you can build anywhere, so long as you can get there.
- If your commander dies it's all over. Nothing else matters. It's like chess in that regard. Only with hundreds more pieces on the board.

For first few missions that is true, but later on you get more side objectives and technologies to play with, not to mention campaign actually branches - and that's where OWar shines. *jumps around to get attention*
TA campaign sucks. It really, really does. It is not unplayable by any means, but it is often frustrating and its usually just skirmish with limited technology upgrades, and that is about it. Do not get it for SP, I did the same mistake.

You will be better off getting Perimeter, OWar, Earth 2150...

My cousin had that game, man was it awesome ! As soon as that game hit GOG's frontpage I thought of buying it. Unfortunately, my current rig is a low-powered netbook (I know it sucks...), so the choice is quite limited.

I was thinking though, with 1.6GHz (N450), could I still play the game with everything on Low ?

Thanks.

If you have the standard netbook resolution of 1024 x 600, forget it. Expansions wont even launch and whatever resolution you set in the original game, you will get the weird scrolling thingy where you never see the whole screen. The same applies to original war. I think Total Annihilation does support quite a range of resolutions thou.

Yes, I have the infamous 1024x600 resolution that keeps me from playing certain games.
About Cossacks I was quite sure the game wouldn't work because of the proc specs :(

I think I'm going for TA:Commander Pack. Apparently it's an instabuy ! I will search the webz to see the supported resolutions.

Thanks ever so much, it's really nice to have such a great community !

The secondary objectives are easy to complete (you will complete them on your first playthrough, except maybe a couple, if you play smart) and you will unlock all the technologies in most cases.
AS for the branching, the USSR and USA branching merge, and that's only the 4 or so last levels of each campaign, so really it is 2 campaigns and half in total. Does NOT compare to Cossacks on the "replay-value" category.

But they, talking to a Czech about OW is like talking to a French about LBA :)

Total Annihilation has 50 missions, Core Contingency 25 and the Battle Tactics 100. This is without counting skirmish maps.
The number of units is so vast that you can experiment without end, combining ground, air and water units.

TA:Kingdoms is a fantasy spinoff and was not that well received. It's focus is on storytelling through a long campaign.
The biggest problem is that the engine is better suited for tanks, mechs and such units, so that your knights act and are animated like robots.