Riding on a backstop Sentinel

Posted May 13th 2020, revised May 16th

Associated movies

  • BCM427 - Heroic; Balancing on a backstop Sentinel (6:51)
  • BCM428 - Heroic; Return trips (6:50)
  • BCM429 - Heroic; Stunt boarding (6:52)
  • BCM431 - Heroic; More examples (6:53)
  • BCM432 - Heroic; Crouched view (5:27)

When I posted the original version of this article a few days ago along with BCM427, it was titled 'Balancing on a backstop Sentinel'. Soon afterwards though, I embarked on more play and found new potential. Now that I realise you can get a proper ride out of things rather than just balancing somewhat statically, I've re-titled the article to reflect that, and now have some revision to do. So here it is.

Supported in mid-air

I described the 'backstop Sentinels' in my article about blocking them, but here's another bit of fun you can have with them which is rather more challenging. Namely, drop or jump onto one soon after it spawns (when it'll be ascending at a shallow angle), and try to balance on top. There are two main challenges you can go for here, which I'll elaborate on shortly. One is to balance as long as possible. The other, a possibility I only realised later, is to ride the Sentinel back to where you came from!

Convenient checkpoint

For this activity you'll want to've got a checkpoint just before the Sentinels spawn, and you should preferably be standing near the edge of the opening you've chosen (left or right, as you look out). For the left you can set things up just as I showed at the start of BCM426. For the right, see the start of BCM428. With a convenient checkpoint like this, you'll be able to make repeated tries with minimal delay.

Dropping down early

Boarding basics

In regard to boarding a Sentinel, to start with I'd suggest dropping onto it early (see pic). On the left, you can actually see part of the Sentinel when it spawns and is still stationary, and you can use that as your prompt to drop down. That may be easiest. Alternatively you could just get used to dropping at the right time (still pretty easy), or you could even time things based on the sound of the Sentinel.

On the right, the Sentinel will initially be obscured because that opening protrudes somewhat (the ship got warped in the crash), and you won't be able to board so early. The Sentinel will already have significant speed by the time you see it, but that's not a huge problem.

How the Sentinel is affected

A Sentinel's normal behaviour is to cruise up at a shallow angle, heading away from the ship, then when it gets to the approximate height of the opening, it turns and cruises in. Your presence aboard interferes with this in various ways.

Vertical mode - relatively stable

When you land on it and you're quite off-centre, close to slipping off, it's potentially still able to ascend fairly fast, and perhaps even at close to full speed. But if you get sufficiently well on top, it tends to pause and look up at you, adopting a vertical or near-vertical attitude. In that state it only ascends very slowly or sometimes perhaps even not at all (it's hard to tell), though if you do a jump it can briefly put on a spurt, being free of you. It drifts around but will probably lose interest in you after a while, turning and starting to do more climbing. It may go vertical again later though.

If and when the Sentinel gets sufficiently high or near the opening, it turns and tries to get there, heading for home so to speak. This isn't always level flying though. Sometimes it still has to climb, and can end up going vertical or near-vertical again, near the opening. Also, sometimes it arrives too low and essentially acts as if blocked by the ship wall. In such a case it can become hostile, trying to fire up at you.

Arrgh! Lost it!

Note: when vertical it often does some 'twitching', just like covies and Flood can do when you stand on top of them (e.g. see my movie BCM423 on the hidden thirsty Grunt). It's oscillating between two orientations.

Balancing as long as you can

One challenge you can take up is to balance on the Sentinel as long as you can (while it's still moving around that is; ultimately it might become static outside the opening). Initially you'll probably be struggling to stay on for even a couple of seconds, as there's precious little grip and the Sentinel will be moving around somewhat - and that's if you didn't just bounce straight off in the first place! As it moves, you'll need to make fine adjustments to stay with it, and it's rather easy to over-adjust and fall off. That's the main difficulty really. Once you've got some sense of control though, you should be able to start getting some long balances. My record now stands at 2 minutes 35 seconds.

Crouched close-up view

If you crouch, you can get a very nice close view of the Sentinel (see pic) and can more easily perceive slow ascent. However, it can be awkward trying to stay on. More awkward than standing, that is. You have less traction (or that's what it feels like) and can't respond as quickly, so it takes some getting used to. See BCM432 for some examples.

If going for a long balance, it can be worth eliminating your Sentinel's buddy beforehand, otherwise it'll cruise into the ship and may fire at you from within, something which took me by surprise the first time, as seen in BCM427. Eliminating the first Sentinel is easily done with either plasma fire or an early tag; then you can board the second.

Making a return trip

Another challenge - which makes a very nice trick - is to make a return trip, riding the Sentinel back into the opening from which you came. It's quite hard to stay aboard when the Sentinel turns and heads for home though. My advice is to be facing that way and stay towards the front, also doing some forwards movement. Otherwise you'll quickly slip along the top and off the back. See BCM428 and BCM429 for some of my early examples, and BCM431 for examples where I'd got better at it.

Heading for home

At the opening itself, you might want to duck (if the Sentinel is flying almost level), to avoid getting pushed off by the top of the opening. Or you could make a jump for it. However, that's not usually needed.

After you return, the Sentinel might be left behind outside, either below or above, seemingly having navigation trouble. That's fairly common. Also, it might fire at you.

If you want a quick return, there are tactics you can use to help. One is that if the Sentinel goes vertical, repeated jumps will let it climb, hastening the time at which it'll finally turn and head for home. Another is to avoid having the Sentinel go vertical at all; try keeping a bit off-centre so it climbs (I was doing this quite a bit in BCM431). Another is to board it relatively late so it's already quite high. With a running jump (see the section on 'stunt boarding' coming up), and particularly a boosted running jump, you can board it so late that it'll turn to head for home within just a few seconds.

Landing a turning jump

Stunt boarding

If you want to get showy, try boarding with a running jump, as seen in BCM429. With good timing it's not as hard it sounds.

To get even more extreme, add a grenade blast for boost, so you're actually grenade jumping onto the Sentinel. This can give you extra distance of course.

Another idea: try doing a half-turn during your jump, so that when you board, you're facing towards the ship. It's very hard to land backwards like that (you 'll need to hit it just right), but you get a nice view of the other Sentinel if you're boarding the lead one.

Mid-air transfer

If you board the lead Sentinel in a pair, an interesting possibility arises: that of performing a mid-air transfer to the second! Moreover, see if you can get a return trip involving a mid-air transfer. A pretty amusing trick I'd say - demonstrated at the end of BCM429 and later also in BCM431 (multiple examples, including some where I tag the first Sentinel as i transfer to the second). You'll probably find it easiest to transfer with a jump, but it's also possible to just walk onto the second Sentinel if it comes close enough.