On the note of the virus points, yeah, 200 is way too much per one part. A max of 100 sounds much more reasonable.
I do think some base costs for virus points per enemy bot need to be changed, though. I dont think the actual mechanics of how viruses work needs to be changed at all, after having experimented with it quite a bit, but some bots are definitely more powerful/useful than others when it comes to this. DoomBots, CommandBots, er...... blanking out on robot names here, I havent been awake long.... but various bots need to be a bit higher in cost. I dont think they need to be utterly ridiculous when it comes to cost... for example nobody is really going to virus something if it costs 100 or 120 points at mid-game, however useful it might seem.
I think having the base virus level always be just 5 plus the robot level is part of the problem here. Bot should probably have specific base values in addition to that. That CommandBot, for instance; give him a base of, say, 30 or 40. At mid-game he'd be potentially around 50-65 to virus, which sounds more reasonable for that particular bot, wheras in my current game (where I am halfway through), the CommandBot is about.... 20-ish, to virus? Too easy to get him. Same with various other bots.
If a bot is either very strong, or provides a useful special effect, it should be expensive to virus. I should have to consider the costs carefully; do I take this really strong bot, that has lots of attack power or provides such-and-such special effect yet costs 70 points, or do I try to grab multiple smaller, simpler bots for the same total cost, giving the enemy more targets they must shoot at and more distraction? Choices like that are what should be happening here with this mechanic.
This is all based on Expert mode, this feedback, so that's worth keeping in mind, probably. But yeah, I think the actual mechanics of virusing stuff is perfect, but the costs are definitely not. And 200 points coming offa 1 part is definitely too much.
As for viruses breaking stealth, I dont really think that'd need to be the case if those per-bot costs are corrected. One of the reasons virusing even works at all, particularly on expert, is BECAUSE it doesnt break stealth. Many situations where a virus is needed would basically REQUIRE an Exo sacrifice if that was the case. Perhaps instead, actions that dont break stealth could have a higher stealth cost, such as perhaps taking 5 points away on that turn instead of always just 1.